4x4 Dictionary (4x4Power Apr-May00)

[Steve83]

I was just digging up some old files & ran across this OCR. Much of the first article (A-H) is somewhat comical, but still reasonably accurate.

To find a term or abbreviation (on this or almost any web page), hit CTRL+F <Find> and type the search term, then press ENTER as many times as needed.


p. 32 4x4 POWER APRIL 2000

Easy Steps to Learning the Off-Roader's Lexicon
Every hobby has its own language. One of the hardest steps of taking up something new is learning the terminology. Colorful phrases are also a part of any insider-speak, so we've taken it upon ourselves to demystify the technical words, phrases, and other jargon that comes with the 4x4 territory.
A
A-arm (limuhtud travul) n. Triangular-shaped suspension component with two pivot points connected to the truck's frame and one point attached to the steering knuckle by a ball joint.
ABS (loos durt hil skid) n. Antilock Braking System
add-a-leaf (cheep lift) n. An extra spring leaf that is added to the spring pack.
airbag (towtuld rig) n. 1. Passive restraint comprised of an inflatable bag hidden within the center of the steering wheel and sometimes in the dashboard in front of the passenger, which deploys in the event of a front-end collision and prevents the passenger(s) from being thrown into the dashboard, steering wheel, or windshield. 2. Suspension device, consisting of an inflatable rubber bladder that augments or replaces a truck's steel springs and allows changes in ride height and increases cargo-carrying capacity. 3. A backseat driver.
air box (truk lung) n. Enclosed chamber that routes fresh air to the carburetor or intake manifold. Some trucks use an air box with an integral filter; some use a remote filter at the air box’s intake duct.
air dam (wurthlez ov-rode) v. Full-width panel just below the bumper, designed to reduce or modify airflow under the truck, which improves aerodynamics but limits ground clearance.
air-down (dee-flat) v. To lower the air pressure in tires (or expensive sneakers). Airing down increases traction and smoothens out the ride over rough terrain.
air/fuel mixture (stow-kee-o-met-rik) n. The ratio of air to gasoline that makes the fuel mixture. Theoretically, the perfect ratio is 14.7.
Air Locker (max trackshun) n. A locking differential manufactured by ARB that uses compressed air to engage the side gears.
all-wheel drive (for-n kar stuf) n. A system in which all four wheels are driven through 3 differentials. Most lack a multi-range transfer case.
analog (e-z tu reed) adj. Gauge or display that shows a reading such as mph, rpm, or fuel level with a dial and moveable needle indicator. Antonym: digital.
anodize (red or blew) v. To apply a colored or clear oxide coating to an aluminum component through an electrical charge.
anti-sway bar (limuhtud travul) n. Suspension component that prevents excessive side-to-side body sway. Synonym: sway bar
approach angle (noz drag) n. The maximum incline angle that a truck can climb or descend without hitting its front.
ARB (smawg polees) n. 1. Air Resources Board. 2. Manufacturer of the Air Locker differential and other off-road products.
aspiration (hi-ur pay-ng jawb) n. An engine's breathing system.
axle hop (bun-ee hawp) n. When a truck's axle housing rotates in the same direction as the tires under acceleration, then snaps back to its original position relative to the chassis. Sometimes, this motion is repetitive until the driver reduces the degree of acceleration. Synonym: Axle wrap
axle housing (frunt or rer end) n. Exterior non-rotating housing that contains the axle shafts, differential, and the gears that drive the wheels.
axle wrap (no trakchun) n. A condition where the rotational load from an axle is placed on the leaf spring. Springs are flexed into an "S" shape, storing spring energy until the tires slip.
B
backpressure (ohld seetz) n. l. Resistance to the free flow of exhaust gases. 2. A common condition on extended desert trail rides with mixed company and no trees in sight.
backspacing (ov-set) n. The distance between a wheel's outer inboard edge and its mounting flange.
baffle (us tri-ing tu bee clevur) n. l. Plates, panels, or barriers inside a muffler that reduce sound. 2. A condition resulting from mysterious vehicle vibrations.
balance tube (ecks pipe) n. Short, laterally positioned pipe connecting the exhaust pipes on a dual-exhaust system. Used to equalize gas pressure between the two pipes.
ball joint (no fun tu chanjuh) n. A flexible joint consisting of a ball in a socket, mainly in front suspensions because it can accommodate a wide range of angles.
basecoat (duhl) n. 1. Initial coat of paint on top of the primer coat. 2. The bottom layer when dressing for winter 'wheeling.
BDC (bee-dee-see) n. Bottom Dead Center, the lowest point of a piston's travel within the cylinder.
bead (beed) n.1. The inner lip of a tire that attaches to the wheel. The exterior rubber bead conceals an embedded wire reinforcement. 2. In welding, a narrow half-round line where two pieces of metal have been joined.
bead lock (zero psi) n. A two-piece system that clamps the tire to the rim, especially helpful when airing down your tires for off-roading.
beater (reel truk) n. A truck that is rough or dented on the outside but might be mechanically sound. Synonym: Bomber
beefed-up (bilt) adj. 1. A 4x4 that is stronger than stock. 2. An after-dinner condition on the trail.
beltline (krom strip) n. 1. Body line running from front to back on a truck's side that visually separates the lower body from the lower edge of the window assembly. 2. A measurement that increases as we get older.
bench race (bee-ess) v. To talk about your truck and your driving feats as if they were fish stories. bezel (krom ring) n. Trim ring, usually chromed or polished, that surrounds headlights or gauges. bicycle (tu-wheeling) v. To ride on either both right or left-side wheels.
bikini top (va-va-voom) n. 1. A soft top that covers only the front seats and leaves the rear uncovered. 2. What many of us like our significant others to wear on the trail.
bellhousing (a-dap-tur) n. Bell-shaped enclosure for the clutch and flywheel on a manual transmission or for the flex plate and torque converter on an automatic transmission.
billet (o-vur-uuzed) n. A part machined from a single piece of metal, not a casting.
bleed (him-or-rage) v. 1. To remove air in a hydraulic system by pumping out fluid. 2. What hands often do while working on trucks.
blip (hamur) v. Quick touch of the throttle to momentarily rev an engine.
blower (beeg powur) n.1. Supercharger. 2. Ventilation system's motor.
blown engine (truk for sale) adj. 1. A seriously damaged engine. 2. A supercharged engine.
blow the doors off (wacks) v. 1. To defeat a competitor during a speed contest. 2. To shoot up abandoned vehicles in the desert with a .44 Magnum.
blueprint (think uh-hed) v. To rebuild an engine to its OE design specs, machining and checking the weight, size, and fit of each component against a factory blueprint.
body roll (sway) n. 1. Tendency of a truck's body and chassis to lean toward the outside of a turn as the result of cornering forces. 2. The flesh that protrudes over our beltlines.
bog (hot dam) v. Running an engine below its intended operating range by driving in too high of a gear for the speed or load. n. The mud pit at a mud-bog race.
bogger (n-sane) n.1. A vehicle built for mud racing. 2. One who mud-races.
boiling the balonies (bern-out) v. Spinning the tires.
bolt-on (duzunt x-ist) adj. Aftermarket part or component that can be installed without special modifications or major disassembly.
bone yard (gold mine) n.1. Wrecking yard, junkyard, salvage yard. 2. The Back 40 of many 4x4 owners’ homes.
boost (mor powur) n. The increase in intake pressure above atmospheric pressure provided by a supercharger or turbocharger. Boost is measured in psi.
bore (ko-drivur) n. The diameter of a cylinder. v. Act of machining a cylinder to fit larger pistons.
bored-and-stroked (more kewbs) v. Combination of an enlarged cylinder bore and a lengthened piston stroke, resulting in an increase in overall engine displacement and power; rarely boring.
bottom end (tork) n. 1. The crankshaft, connecting rods, and main bearings of an engine. 2. Power at low engine speed.
bottom-out (plumr-but) v. When the truck's suspension is fully compressed and its bump stops won't allow further suspension travel.
boxed (ree-n-forced) v. Strengthen a frame by adding a metal plate to an open-channel frame rail or crossmember, thereby turning a three-sided frame rail into a four-sided rail.
brake (stopr) n. 1. A hydraulic & mechanical system that slows the rotation of the tires. 2. What your co-driver screams just before a rollover. v. 1. To slow down or stop. 2. A word often confused with “break”.
brake fade (%&*@!) n. A loss of braking power, the result of the brakes' friction surface or the brake fluid overheating.
break (tu-much-fun) v. What happens on a good trip to everyone’s vehicle but yours.
bulletproof (stowt) adj. An allegedly indestructible truck or component.
bump (dent) n. A horizontal obstacle. v. 1. To blip the accelerator. 2. To back off an obstacle, then hit it again with momentum.
bump steer (wawn-dur) n. A situation in which the steering jerks when a truck encounters a bump in the road. Bump steer is often caused by improper steering geometry.
bumpstick (beeg, fat, and hairee) n. Camshaft.
bump stop (bawtum out) n. Rubber or urethane block used to limit suspension compression travel.
burnout (long month) v. Deliberate spinning of the rear tires to heat and clean the tires' tread in preparation of maximum acceleration from a standing start. Can also be used to impress onlookers.
butt-scratcher (noz-pikurs) n. A trail obstacle that scrapes on a truck's rear end.
C
cam (bumpstik) n. An eccentric device that converts rotating motion to reciprocating movement. (Camshaft).
camber (travul-trailur with a hed kowld) n. The tilt of the front tires toward or away from the center of the truck relative to vertical. When the top of the tire leans out the camber is positive; if the tire leans inward, camber is negative.
cam duration (kam-du-ray-shin) n. Amount of crankshaft rotation expressed in degrees that a cam holds the intake or exhaust valves open.
cam lift (kam lift) n. Distance, expressed in thousandths of an inch, at which a cam opens the valves.
candle-power (Y2K ee-lek-trisitee) n. A light brightness rating. Not all manufacturers use the same method to determine candlepower.
carbon fiber (hi-tek) n. A lightweight cloth material, such as rayon, saturated with a liquid chemical that hardens in the cloth, resulting in a material stronger and lighter than steel, aluminum, and most exotic metals.
caster (fish oil) n. The fore or aft tilt of the steering axis relative to vertical. Lifting a truck can cause too much negative caster, which results in wandering.
cat-back system (muflur/tailpipe) n. Aftermarket exhaust system that attaches to the outlet side of the catalytic converter and consists of a free-flow muffler, new tubing, and mounting equipment.
catalytic converter (smog crap) n. An emissions control device that routes exhaust gases through an oval-shaped canister filled with palladium and platinum pellets, thereby converting the toxic exhaust gases to water vapor, carbon dioxide, and less-toxic gases. Synonym: Cat
CB (gud bud-e) n. Citizen's Band radio. A two-way radio commonly used for communication between trucks on the trail.
center disconnect (dawg clutch) n. A four-wheel drive system that engages the front axles at an inboard location rather than the outboard hubs.
center of gravity (tip o-vur) n. The center of a vehicle’s mass. It can change dramatically due to passenger load and cargo.
cherry (puss) adj. Clean, in unusually fine shape.
CFM (see-ef-em) n. Cubic feet per minute, generally used to measure airflow through a port, intake manifold or carburetor; a system used to determine carburetor and fuel injection capacity.
chain drive (can stretch) n. A system in which a chain and sprockets drive gears instead of the gears being meshed together.
chick-deflector (rus-tee Scout) adj. Repulsively ugly vehicle. Antonym: Chick magnet.
chicken-handle (wussee bawr) n. A handle for passengers to grab when the going gets rough; also known by other, unprintable names.
chip (PROM) n. A computer's microprocessor. v. A nick in the paint.
chirp the tires (schmok) v. To shift quickly during hard acceleration so that the tires momentarily lose traction.
chunk (chunk) n. Slang for the ring-and-pinion gear assembly inside a differential housing. v. When parts eject from their functional location.
clip (noz) n. A truck's entire front sheet metal section, including the fenders, hood, and cowl.
coil-over (x-pensiv shoks) n. A suspension that uses shocks with an integral coil surrounding the shock body, often used with custom-fabricated multi-link suspensions because they offer the advantages of easy preload and ride-height adjustments, lots of wheel travel, and accurate spring dampening rates.
collector (wiz guy) n. Device that collects exhaust gases from the exhaust manifold's (or header's) primary tubes and routes them into a single exhaust pipe.
color-sanding (waste uv time) v. Light sanding process with 1,000-grit-or-finer sandpaper after a truck has been painted.
combustion chamber (fire in da hol) n. A cavity within the cylinder head, just above the piston, where combustion takes place.
compression ratio (CR) n. The ratio of cylinder volume with the piston at BDC to the volume remaining in the cylinder chamber when the piston reaches TDC. The greater the difference, the higher the compression ratio, generally producing more power. If the compression ratio is too high, however, it can cause detonation and an Increase in pollutants.
contact patch (fut-print) n. Portion of a tire tread in contact with the road surface.
Cornbinder (dependably uglee) n. Slang for any 4x4 made by International Harvester because the company is known for making farm equipment. Synonym: Binder
crank it (build bicepz) v.i. To turn the steering wheel hard left or right. 2. To start the engine.
crankshaft (krank) n. Shaft with large, U-shaped cranks that are connected to the pistons' connecting rods and transforms the pistons' reciprocal motion to a rotational motion, which powers the drive train. Synonym: Crank
crawl-ratio (granne geering) n. The lowest gear ratio in the truck, found by multiplying the first gear ratio of the tranny by the low-range gear ratio of the transfer case by the axle gear ratio.
cross-drilled crank (swis-cheezed) adj. Crankshaft with additional lubrication holes drilled opposite the existing main journal oil feed holes, providing improved high-rpm bearing lubrication.
curb weight (reel wate) n. Total weight of a truck with the fuel tank full, the engine oil at its proper level, and the cooling system full, but without a payload or passengers.
CV joint (ript boot) n. Constant Velocity joint, a joint designed to produce smooth rotation in a driveline regardless of the angle of flex. Commonly found on front-drive axles. Often confused with a “double-cardan”, which is an assembly combining 2 U-joints to reduce driveline vibrations.
cylinder head (hed) n. The part of an engine that contains the valve train and the combustion chambers and covers the tops of the cylinders and pistons.
D
dechrome (euro-look) v. To strip a truck of its chromed or polished exterior body trim, including filling the body trim's mounting holes.
deck (rite-jab) n. The surface of the engine block on which the head gasket and cylinder sit.
degree-ing a cam (spin thu wheel) v. Using a dial indicator and a degree wheel to verify that a cam's lift and duration is accurate.
departure angle (but-drag) n. The maximum angle a truck can descend before hitting the rear bumper or other components located behind the rear tires.
Detroit Locker (ole standby) n. A popular brand of mechanically locking differential.
dial-in (fine-toon) v. 1- To set up a truck's engine, chassis, drive train, stereo, or other system so that maximum performance results. 2. To set up a mechanical component for trouble-free operation.
ding (no wureez) n. Small dent on a truck's body.
direct ignition system (no plugwirz) n. Ignition system that has no distributor; ignition is sent directly from the multiple modulators (coils to the spark plugs).
directional tire (mountrite) n. Widely, but incorrectly, thought to mean a tire with an asymmetrical tread that is designed to produce superior traction when rotating in one direction only. Actually, the directional nature refers to the sidewall construction. The weaker wall MUST be mounted inboard since the outer wall sees more load.
double-line (strong pul) n. A type of winch rigging that runs the cable to an anchor point through a snatch block and back to the vehicle, thereby doubling the pulling power.
Double-pumper (mor fuel) n. A four-barrel Holley carburetor with mechanical linkage to open the primary and secondary barrels and mechanical accelerator pumps in both the primary and secondaries.
drag link (shuldn't drag) n. Steering link that connects the pitman arm to the steering arm.
drop the hammer (spray partz) v. To accelerate rapidly from a stop.
droop (jounce) v. Any downward suspension travel.
dropped pitman arm (angul fixur)n. An offset arm that lessens the angle between the steering box and drag link.
dually (tow-a-sor-us max)n. A truck that has two rear tires on each side. “DRW”
dual plane (mor tork) adj. An intake manifold with runners that do not share a common plenum, usually designed for low- to midrange engine performance.
dyno (bluf-callur) n. Abbreviation for dynamometer, a tool used to measure engine torque either at the flywheel (engine dyno) or rear tires (chassis dyno).
E
E.C.U. (brane) n. Electronic Control Unit, computer unit for engine management. Synonyms: EEC, PCM, MCU.
E.F.I. (runz sidewayz) n. Electronic Fuel Injection; computer-controlled equivalent of the carburetor.
E.G.R. (pas gas) n. Exhaust Gas Recirculation, an emissions-control device that re-introduces burned exhaust gases to an engine's combustion chamber to reduce combustion temperatures, and thereby reduce the formation of oxides of nitrogen (NOx). NOx combines with rain to produce acid rain.
electronic ignition (no pointz) n. Ignition system that uses transistorized circuits instead of breaker points.
E.O. Number (smog I.D.) n. Executive Order Number, the number assigned to a part by the California Air Resources Board (CARB) when it becomes legal to use on emissions-controlled vehicles.
exhaust backpressure (beeg mexuhcan meel) n. Resistance to the free flow of exhaust gases through an exhaust system.
exhaust headers (towtulee toobular) n. Performance exhaust manifold built from steel tubes that is designed to speed the flow of exhaust gases exiting the cylinder head(s).
exhaust manifold (O.E. stuf) n. Tubular cast-iron component that routes exhaust gases from the cylinders to the exhaust system.
F
fairlead (kaybul control) n. A steel guide installed onto a winch mount to help direct the winch cable. Fairleads come in two styles: roller, which uses steel rollers, or Hawse, which features a simple bracket with large radiused edges for the cable to ride against.
fan clutch (mind of itz own) n. Thermostatically controlled clutch device that engages or disengages a mechanical radiator cooling fan according to the engine's cooling needs.
fish eye (bad paintur) n. Crater-like spots that appear in a new paint job due to contamination from water, oil, or a silicone-based material.
flathead (co-werkerz) n. An early engine design that located the valves in the block beside the cylinders, rather than the head (overhead valves) as is currently done.
flat spot (no powur) n. Momentary decrease in engine power at some point within the power band.
flat-top (smooth slug) n.1. A piston without a dish or a dome. 2. A popular '50s haircut.
forced induction (mor air) n. Supercharged or turbocharged.
four-banger (no tork) n. A four-cylinder engine.
four-bolt main (buildable) n. An engine whose crankshaft's main bearing caps are held in place by four bolts each.
freewheeling (unloked) v. When the front hubs are unlocked and the wheels spin because of momentum rather than power.
frenched (smooth) v. Custom bodywork that recesses a part, such as door handles or taillights, into the sheet metal.
fuel injector (skwerter) n. Electromechanical device that squirts fuel into an engine.
full house (raze the bet) v. An engine, suspension, body, or interior that has received every possible modification or upgrade.
full-floater (no wheel ejekt) n. An axle assembly designed to hold the weight of the vehicle on the axle housing instead of on the axle shafts; has bearings at both the differential and wheel ends.
G
gas shock (boingur) n. Damper shock absorber with two separate compartments, one containing hydraulic fluid, one containing nitrogen gas. The gas keeps pressure on a flexible (in some cases moveable) separating disc that, in turn, keeps pressure on the fluid, thereby reducing the fluid's tendency to foam during aggressive driving.
G-force (jee-fors) n. Measurement of the force generated during cornering, acceleration, or deceleration, expressed in units of gravity.
glass packs (throw-tee) n. Tubular style of muffler that uses fiberglass packing to absorb sound. gnarly (tuf) adj. Difficult portion of a trail that may or may not make you nervous. Synonym: exceptional.
granny gear (crawlus maximus) n. An extremely low first gear in a manual transmission. For example, an SM465 has a 6.55:1 first-gear ratio.
grenade (deestroy) v. Catastrophic failure of a part. Engines, transmissions, and axle assemblies can ail grenade.
greenhouse (dawghows) n. Upper portion of a truck's body; the structure above the beltline, including the roof, the windows, and the pillars. Synonym: office.
ground effect (wurthlez ov-rode) n. Reduced airflow under a truck provided by an air dam and side skirts. Less pressure underneath a truck allows the air passing over its top to push downward, thus creating an improved grip on the road as well as improved top speed and fuel efficiency. Impedes ground clearance in 4x4s.
gumbo (jambalaya) n. Deep, sticky mud.
gun it (hamur down) v. To deliberately rev an engine.
gusset (beef) n. Triangular metal support used to add strength; it is welded in place where two frame rails connect or where two tubes of a roll cage are welded together.
GVWR (jee-vee-du-bull-you-r) n. Gross Vehicle Weight Rating, the rated combined weight of a vehicle and its cargo.

p. 72 4x4 POWER MAY 2000
H
hair dryer: A turbocharger unit.
halogen light: High-output headlight or driving light that has a halogen gas inside the bulb. When surrounded by a halogen gas, the bulb's tungsten filament can carry a higher current, thus producing a more brilliant white light.
hammered: 1. A truck that's thoroughly destroyed. 2. A truck that has a chopped top or a severely lowered suspension.
handle: 1. The nickname you use on the CB. 2. Passenger hand loop ("chicken bar").
Hasselhoffing: The act of mugging for the camera while driving.
H.E.I.: High-Energy Ignition, a powerful and reliable GM distributor assembly with a self-contained coil.
heliarc welding: A form of tungsten Inert gas (TIG) welding used primarily on aluminum and stainless steel.
helicoil: Stripped-thread repair system, consisting of small coil spring inserts that thread into place on damaged female screw threads.
high-centered: When a truck Is firmly stuck, usually caught on its frame on an obstacle unable to move.
hi-po: High-performance.
hole shot: Beating a competitor at the start of a race; coming off of a dead stop quicker; coming out of the hole quicker.
hook up: To gain traction.
hoops: 1. Wheels, usually billet alloy construction. 2. Tubular shock mounts. 3. Driveshaft safety restrainers.
hub: 1. Center section of a wheel, including the mounting holes. 2. The rotating end of an axle assembly to which a wheel is mounted.
huffer: A belt-driven supercharger.
hydraulic'd: (hydro-locked) Past tense only, said of an engine that has been submerged in water and has sucked water into its cylinders through the intake and will no longer rotate because the pistons moving up the cylinders cannot compress the water.
I
I.F.S.: Independent Front Suspension. A type of suspension system that allows the two tires on one axle assembly to move separately.
intake ports: Passages within a cylinder head that routes air and fuel to the Intake valves.
J
juice box: An automatic transmission. Synonym: slush box.
K
kick-down: Quick downshift on an automatic transmission when the engine is given full throttle.
kicker shocks: Shocks mounted in a near horizontal position between the axle housing and the leaf springs. Kicker shocks are valved with a high rate of compression damping and are intended to reduce axle wrap.
kick-up: Section of a frame that is curved up to clear an axle housing.
L
ladder bars: Longitudinal suspension control arms that connect the axle to the frame, preventing axle wind-up and hop.
lash: Amount of clearance between a valve and a rocker arm or between a rocker arm and a lifter or pushrod.
lateral link: Tubular suspension rod that positions the axle housing so that side-to-side movement is minimized during cornering.
L.E.D.: Light-Emitting Diode, a small semiconductor that lights up when current is passed through it. Used on some dashboard displays and taillights.
lifted: Any 4x4 that is raised either by a suspension or body lift.
lift-block: A spacer placed between the axle assembly and the springs to lift a truck inexpensively. These are only safe on rear axle assemblies.
light it off: Start an engine.
limited-slip differential: Final-drive system where the two axle shafts are mechanically connected with a series of clutch-like plates to reduce wheel spin on slippery surfaces by its tendency to transmit the engine's power equally between the two axleshafts.
line: 1. A driver-selected path that gives a truck the best route to climb over an obstacle or through a pathway. Choosing the right line is essential to successful four-wheeling. 2. A hose or tube.
locked in: To have engaged the manual front hubs into the lock position.
locker: A device in a differential that sends engine power to both wheels regardless of traction.
lockers front and rear: One of the most common truck-owner fibs.
Loctite: A chemical used on fasteners to maintain torque.
long-block: Engine assembly consisting of a cylinder block, a crankshaft, a camshaft, bearings, pistons and rings, connecting rods, an oil pump, an oil pan, a timing cover, seals, cylinder heads, and an intake manifold.
loud pedal: Accelerator. Synonyms: go pedal, skinny pedal.
low gears: Gears that increase the amount of reduction in the transmission, transfer case, or axle. In an axle, they are expressed as the ratio of ring-gear teeth to pinion teeth, so low gears are numerically higher than high gears. (Example: 4.10 gears are lower than 3.55 gears.) Rock crawlers typically have low gears.
low-lock: To have the transfer case in 4-Lo.
M
mandrel bend: Hydraulic or mechanical tube-bending machine that uses dies and mandrels (forms) to bend tubing in such a manner that the walls don't collapse.
manifold cooking: Using a hot intake manifold as a heat source for cooking on the trail. Burritos and cans of beans are favorite manifold delicacies.
MAF: Mass Airflow sensor, a device that measures the amount of airflow into the intake manifold. This information, as well as data from other sensors, is sent to the engine's computer, which calibrates the optimum air/fuel mixture and adjusts the EFI system as required.
meats: Tires, particularly large, aggressively treaded ones. Synonym: skins, shoes.
metallic paint: Custom paint containing very fine, glimmering metal pieces that make the paint sparkle and reflect light.
MIG: Metal inert gas welding is a wire-feed welding system that uses argon gas as a shielding agent for the weld. Steel, stainless steel, aluminum, and other metals are commonly welded with a MIG welder.
mill: 1. Engine 2. Milling machine.
modular wheel: Custom or racing wheel with an inner, an outer, and a center section that are bolted or riveted together.
monochrome: Styling inspired by European performance cars where the bumpers, grille, body trim, and door handles are painted the same color as the body.
mountain motor: Big-block engine, typically bored and stroked to at least 500 cubic inches.
Mouse motor: Chevy small-block V-8 engine, named Mouse because of its small overall physical size, and because, some say, GM executives wanted to scare Chrysler's "elephant" Hemi engine with the new, powerful small-block Chevy.
multi-link: Solid-axle suspension design where coil springs are used instead of leaf springs, and the axle is located by longitudinal and lateral suspension control arms, or links.
N
nail it: To apply full throttle.
negative offset: When the wheel's mounting surface is outboard of its center line.
normally aspirated: An engine that relies on vacuum through its intake manifold and cylinders to draw in an air/fuel mixture; an engine without forced-induction (supercharger or turbocharger).
N.O.S.: 1. New old stock; original equipment, unused parts for vintage trucks, often found in their factory cartons at dealerships. Antonym: repro, reproduction. 2. Nitrous Oxide System; A system that introduces laughing gas into the engine’s intake system to boost horsepower.
O
OE: Original equipment. Synonym: stock.
OEM: Original equipment manufacturer - same brand as stock.
oil gallery: Small passages within the engine block and cylinder heads through which lubricating oil circulates. Synonym: oil journal
off-camber: A situation in which the truck is sideways on an incline, increasing the likelihood of a rollover.
one-off: 1. Custom part or component that is fabricated from plans; no other identical copy exists. 2. Wide-production modifications to an existing vehicle, such as a Saleen Explorer.
out to lunch: Worthless, a truck that doesn't run well or look right.
oversteer: Cornering condition where the rear tires slide toward the outside of the turn.
P
panhard bar (or rod): A transverse link (rod that attaches to the truck's frame at one end and to the axle housing at the opposite end), providing lateral positioning of the axle housing relative to the chassis.
paperweight: A part that's broken beyond repair can be used as an excellent paperweight.
payload: Maximum weight a truck can carry, calculated by subtracting the curb weight of the truck and a 150-pound allowance for each passenger from the gross vehicle weight rating.
peg-leg: An open differential. Synonym: one-legger.
pickle fork: Fork-like tool used to separate suspension components, such as ball joints and tie rod ends, for repair.
pinion angle: The angle of the pinion yoke on an axle housing in relation to its drive shaft.
pitman arm: Steering lever that converts the rotary motion of the steering box to the linear motion of the steering system's center link.
plenum: Box or cavity at the intake manifold's entrance that stores the air/fuel mix for distribution to the intake runners.
plow: Understeer.
port injection: Electronic fuel-injection system that injects fuel directly into the cylinder head ports.
posi: Short for Positraction, a limited-slip differential used by General Motors. The term is often used generically for any limited-slip device.
positive offset: When the wheel's mounting surface is inboard of its center line.
prerunner: An off-road truck that's built to pre-run a desert race course so that the driver can study and practice on the course before the race.
primer: Basic initial coat of paint; provides adhesion for the top coats of paint.
progressive-rate springs: Suspension springs that become progressively stiffer as they are compressed.
proportioning valve: Hydraulic braking valve that varies the braking force at the front or rear wheels, depending on pedal pressure, load, and weight transfer, to reduce or eliminate wheel lock-up.
P.T.O.: Power take-off, an accessory powered by engine output, usually a winch.
pumpkin: The center section of an axle housing that contains the differential carrier and gear set. Synonyms: coconut, chunk, diff housing.
pushrod: Thin metal rods that transmit the motion from the camshaft and lifters to the rocker arms, and thus operate the valves on an overhead-valve (OHV) engine.
Q
quad: 1. Four-barrel carburetor. 2. A four-wheeled all-terrain vehicle.
quarter-panel: Body shop term for the front or rear corner sheet metal assembly.
R
radius arms: Brackets used by Ford that locate the front axle housing on coil-spring suspensions. Dodge and Jeep use similar ones, which are called trailing or control arms.
rack-and-pinion: A steering system that uses a pinion gear at the end of the steering shaft to engage a horizontal toothed bar, the rack, which is attached to the tie rods and the steering knuckles.
rake: When the front end of a truck sits lower than the rear.
ramp break-over angle: The angle formed by lines drawn from the front and rear tires' contact patches and the midpoint of the wheelbase on the chassis; the greater the angle, the less likelihood of high-centering.
Rat: Chevy big-block V-8 engines, normally offered in 396ci, 402ci, 427ci, and 454ci sizes. Named because it was a large companion to Chevrolet's small-block Mouse V-8.
rebound: After a suspension spring is compressed by a bump, the spring naturally tries to return to its previous length, extending the suspension upward toward its original ride height.
recirculating ball steering: Steering assembly that uses a worm gear on the end of the steering shaft to turn a sector gear that is within the steering box and attached to the pitman arm. Ball bearings are used between the worm and sector gears for smooth operation, and pass through a tube so they return as they roll out between the gears.
red line: Absolute maximum engine speed, expressed in rpm, at which an engine can/should be operated; indicated by a red line on the tachometer. Synonym: rev limit.
repro: Aftermarket reproduction parts, manufactured to appear, fit, and function as originals. Not the same as OE (Original Equipment) or NOS (New, Old Stock), which are both factory-issued parts.
restify: To build a truck that is basically restored but has been updated with modern convenience and performance enhancements.
retrofit: Installing new parts or systems on an older truck for the purpose of upgrading, such as retrofitting a modern fuel-injection system in place of the carburetor.
rev limiter: An adjustable electronic device that restricts engine rpm to a predetermined limit so engine damage does not occur.
ring-and-pinion: Gear set that drives the wheels; the pinion is a gear connected to the rear of the drive shaft, and the ring gear is attached to the differential that turns the axles.
rock magnet: A low-hanging component of a 4x4, such as a ladder bar, that seems to catch on every obstacle.
rock massaging: Body damage caused by rocks and other obstacles on the trail.
rocker arm: Pivoting valve train levers. One end of an engine's rocker arms are moved by the pushrods/lifters and their opposite ends open intake or exhaust valves.
rocker panel: The sheet metal section of a truck's body located below the doors and between the front and rear wheel openings.
roll pan: Sheet metal or fiberglass insert, usually on the rear of a 2WD truck, which covers the gap between the fenders after the rear bumper has been removed.
Roots supercharger: Positive-displacement, belt-driven supercharger; originally designed in 1859 by Francis Roots for use as a water pump.
RTI: Ramp-travel index, a measurement of suspension flexibility and articulation that's calculated by dividing the distance the hub's centerline travels up a (usually 20-degree) ramp by the vehicle's wheelbase in inches, multiplied by 1,000.
S
sanitary: Well designed, engineered, and constructed; cleanly built; superior mechanical workmanship. Synonyms: sane, sweet.
semi-floater: An axle assembly that carries the weight of the vehicle on the outer end of the axle shafts, but 'floats' (no vertical load) at the inner ends. These are typically weaker than full-floaters.
serpentine belt: A single engine accessory drive belt that is long and follows a snaking path while driving the alternator, water pump, A/C unit, and power steering pulleys.
shackle: Connector between the rear of a leaf-spring pack and the frame; allows the spring to lengthen as the suspension is compressed.
shaved: Custom bodywork process where a door handle or trim piece is removed, and the remaining hole(s) is filled with metal and smoothed over with filler. Can be used on drip rails, fuel filler caps and doors, tailgate handles, and badges and emblems.
shift kit: Package of high-performance components for an automatic transmission that firms the shifts, alters the shift points, and improves overall performance.
shiny-side down: When a truck rolls over. Synonym: rubber-side up.
short-block: An engine block that has a complete bottom end, Including the crankshaft, rods, pistons, and camshaft, but without the cylinder heads, intake and exhaust manifolds, water pump, and other accessories.
side hill: A portion of a trail that leads across a steep hill instead of up or down. See off-camber.
single-plane manifold: Intake manifold with a single plenum feeding all of the engine's intake runners.
skin: Body sheet metal.
skins: Tires.
slickrock: A type of sandstone made famous by Moab, Utah. Slickrock actually isn't slick and provides excellent traction.
slush box: An automatic transmission. Synonym: juice box.
small-block: 1. A V-8 engine typically having 400 or less cubic inches or displacement. 2. A family of engines of varying displacements that share the same block casting, which is smaller than that of another family of engines from the same manufacturer (the big blocks).
snatch-block: A pulley device used in assisting with getting unstuck; it doubles a winch cable's pulling power.
snatch strap: A thick nylon strap used to pull out stuck vehicles. Synonym: tow strap, yank strap.
spool out: To pull the winch cable off the drum after releasing the brake.
spotter: A co driver who helps guide the driver over obstacles, often using hand signals.
spring rate: The force required to deflect a spring 1 inch, expressed in pounds per inch of spring compression or deflection. The higher the per-inch spring rate, the stiffer the spring.
spun bearing: A bearing that is either worn or frozen and has rotated in its retainer. In an engine, this causes the bearing to block off its oil passage and results in major damage.
stair-step: An obstacle that contains one or more ledges that must be climbed in succession. Stair steps are common on trails that follow washes or creek beds.
stand on it: Full-throttle acceleration.
suicide doors: Custom procedure where a truck's door hinges are moved from the front to the rear, thereby enabling the doors to open from the front. Some Lincoln Continentals were built this way.
swamped: To drown the engine; to drown the truck.
synthetic oil: Manmade lubricants; they generally have a greater capacity to lubricate and resist heat than standard mineral oil.
T
tachometer: Device used to measure and display engine speed, expressed in revolutions per minute. Synonym: tach.
tack welds: Series of small welds, spaced approximately 1 Inch apart, which are used to hold together two pieces of metal until the final welding can be performed.
taco'd: Axle housings, frames, or other components that have been severely bent, usually from jumping the truck.
tail-gunner: The last vehicle/driver on a trail ride. The tall-gunner is responsible for making sure everyone completes the trail.
tall gears: The opposite of low gears, they are represented In ratios that are numerically lower than "low" gears; e.g., 3.08s are "taller" than 4.1Os.
T.B.I.: Throttle-body fuel injection.
third member: A removable differential carrier, like a chunk.
threshold braking: Applying as much pressure to the brake pedal as possible without going to wheel lockup.
throwout bearing: On a clutch assembly, a shaft mounted bearing that is moved from pressure on the clutch pedal and disengages the clutch disc from the engine.
T-case: Transfer case; a transmission bolted on behind a vehicle’s main transmission with a front & a rear output, and found only in 4- and all-wheel drive vehicles. Most 4WDs have a low range; all AWDs have a differential.
tie rod: Steering linkage between the pitman or idler arm and a steering arm that moves the steering knuckles.
TIG welding: Tungsten inert gas welding, also referred to as heliarc welding, usually used for joining aluminum and stainless steel.
timing chain, timing gears: Chain or gears that transmit rotation from the crankshaft to the camshaft.
toe-in, toe-out: Inclination of a pair of front wheels slightly inward or outward as viewed from the truck's front.
torque converter: Fluid coupling between the engine and the automatic transmission. The engine powers a fan-shaped impeller inside the torque converter, which splashes oil onto a turbine (another fan-shaped device), and the turbine transmits its power to the transmission's gearbox.
torsion bar: Suspension spring that looks like a long metal rod. One end is attached to the truck's frame, and the other end is attached to the suspension's A-arm. When the A-arm moves, the torsion bar is twisted and then springs back to its original shape, thus its springing action.
Toyolet: Chevrolet-powered Toyota. Synonym: Chevota.
T.P.I.: Tuned-port fuel injection.
trail boss: The leader of a trail ride.
trailer queen: A vehicle that's built primarily for show and is trailered to events.
TTB: Twin-Traction Beam, a type of Ford 4x4 independent front suspension that utilizes an axle assembly built as 2 similar arms that span the truck. Synonyms: Dana 30IFS, Dana 44IFS, Dana 50IFS.
tubbed: Truck bed fitted with extra-large wheel wells, or tubs, to accommodate Pro Street-sized rear tires.
tunnel ram: Intake manifold with a large plenum and long, straight runners, used for high-rpm engines.
turned turtle: A truck that's rolled upside down. Synonym: rubber-side up.
two-bolt main: Engine block with its main crankshaft caps held in place by two bolts each.
two-wheeling: When tires lift off the ground during a tricky maneuver. Synonym: bicycling.
U
U-bolt: U-shaped bolt commonly used to attach an axle housing to a leaf-spring pack or a U-joint to a yoke.
U-joint: Mechanical joint that can transmit rotary motion while swiveling. Used at both ends of a drive shaft to transmit power from the transfer case to the differential. Synonyms: Hook's joint, Cardan joint
understeer: Cornering condition where a truck's front tires lose grip before the rear tires, causing the front end to slide or push toward the outside of the corner.
unglued: 1. Damaged or destroyed; a blown-up engine has become unglued. 2. The co driver’s usual mental state following a rollover.
V
vacuum advance: Device that advances or retards ignition timing according to the degree of engine vacuum. At low engine speed, there is plenty of engine vacuum, so the ignition is advanced; at wide-open throttle, there is little vacuum, so the ignition remains at its original timing advance.
vacuum secondaries: Secondary carburetor barrels that are pulled open by engine vacuum.
valve lift: Circular, stemmed device used to control the airflow In and out of an engine; operated by the camshaft/pushrods/rocker arms.
valve train: The valve lifters, push rods, rocker arms, and valve springs.
vapor lock: Condition where fuel bolls within the fuel line, fuel pump, or carburetor, causing bubbles to form that impede the fuel flow or cause excessive fuel to flood the carburetor.
variable-ratio steering: Power steering box that varies the steering ratio. When the steering wheel is near center, the steering response is quicker for maneuverability; toward steering-wheel lock, the steering ratio is increased for stability.
ventilate the block: To throw a connecting rod through the side of an engine block due to component failure or excessive revs.
venturi: Carburetor barrel or throat with a slightly narrowed or hourglass shape to its interior. The small, narrowed area speeds up airflow and helps pull the fuel past the carburetor jets and into the air stream.
V.I.N.: Vehicle identification number, a serial number that identifies a vehicle. Most can be “decoded” to reveal much of the vehicle’s original build specifications.
W
wall: To perform at peak power or efficiency.
wheel adapter: Metal plate with wheel studs that allows a wheel with one bolt pattern to be used on a hub with a dissimilar bolt pattern.
wheelbase: Distance from the center of a truck's front wheel to the center of the rear wheel on the same side.
wheel travel: The total distance a wheel can move up and down; affected by suspension travel and wheel well clearance. More wheel travel means a more flexible suspension and more potential traction.
white-knuckle: An obstacle that Is scary enough to make the driver grip the steering wheel extremely tight.
windage tray: An internal oil pan shield, mounted close to the crankshaft and intended to deflect oil away from the crank and near the oil pump pickup.
wiring harness: Major part of a truck's electrical wiring system; a group of wires bundled together.
W.O.T.: Wide Open Throttle. Synonyms: floored, punched, hammered, stomped.
wrist pin: Hollow metal tubular pin that attaches the piston to the connecting rod.
XYZ
zerk fitting: Nipple-like fitting on suspension and chassis parts and on U-joints, through which lubricant is pumped under pressure to lubricate the components' internals.

4x4MAY 2000

[Bonzai]

bookmarked. thanks!

[Steve83]

This seems like the best place to put a list of common automotive abbreviations & terms, even though this might qualify as a technical writeup. I'll let the administrative staff decide. I'll be arranging, editing, & adding links to this list for a while. Abbreviations are only defined as the UNabbreviated terms. Find the full term for the full definition.

To find a term or abbreviation (on this or almost any web page), hit CTRL+F <Find> and type the search term, then press ENTER as many times as needed.



2: combustion code for Otto 2-Stroke-Cycle Piston engines
3-2 Timing Solenoid (3-2TS): A device that controls the timing valve.
3-2TS: 3-2 Timing Solenoid.
2V: Two Valves per cylinder, OR 2 Venturi (barrel) carburetor.
4R44E: 4 speed, Rear wheel drive, 440 lb-ft, Electronic transmission, formerly known as AODE.
4R55E: 4 speed, Rear wheel drive, 550 lb-ft, Electronic transmission, formerly known as AODE.
4R70W: 4 speed, Rear wheel drive, 700 lb-ft, Wide ratio transmission, formerly known as AODE.
4R100: 4 speed, Rear wheel drive, 1000 lb-ft, Electronic transmission, formerly known as E4OD.
4V: Four Valves per cylinder, OR 4 Venturi (barrel) carburetor.
4WD: Four Wheel Drive. A powertrain system which delivers engine power to differentials in each axle. Contrast RWD, AWD, FWD.
4x4 Low (4x4L): Indicates the 4x4 Low range of the transfer case has been selected.
4x4L: 4x4 Low.
5R55W: 5 speed, Rear wheel drive, 550 lb-ft, Electronic Wide-ratio truck transmission, derived from the 4R70W.
A: combustion code for Other
A/C: Air Conditioning.
A/CL DV - Air Cleaner Diverter Valve (carburetor/vacuum)
A/CL BI MET - Air Cleaner BiMetallic valve (carburetor/vacuum)
A/D: Analog-to-Digital signal conversion.
A/T: Automatic Transmission/Transaxle.
ABS: 1. Anti-lock Brake System; 2. A sensor, signal or circuit which supplies rear axle speed data either to the RABS (or RABS-II) module, the 4WABS module, the PSOM, &/or the EEC (for electronic automatic transmission control & return-to-idle). After processing by the 4WABS module &/or the PSOM, the signal is also fed to the VSC & the Bronco overhead console (for temperature adjustment); 3. A type of plastic. Compare PVC.
Absolute Pressure: The pressure referenced to a perfect vacuum. Contrast gauge pressure, which references atmospheric pressure (~14.7psi above perfect vacuum).
ACC: Air Conditioning Clutch.
ACCS: Air Conditioning Cycling Switch.
ACD: Air Conditioning Demand.
ACET: Air Conditioning Evaporator Temperature. AKA Evaporator Air Discharge Temperature
ACON: Air Conditioning On.
ACP: Air Conditioning Pressure.
ACPSW: Air Conditioning Pressure Switch.
ACT - Air Charge Temperature sensor. AKA IAT.
Actuator: A mechanism for moving or controlling something indirectly instead of by hand.
ACV - Air Control Valve (carburetor/vacuum)
AFCM: Alternative Fuel Control Module.
Aftermarket: 1. A general term for the industry that produces non-original parts for vehicles; see SEMA. 2. Non-original vehicle parts. Contrast Direct-Replacement.
AIR BPV - Air ByPass Valve. AKA TAB (carburetor/vacuum)
Air Conditioning (A/C): A vehicular accessory system that modifies the passenger compartment air by cooling and drying the air.
Air Conditioning Clutch (ACC): A sensor, signal, or circuit which indicates status of the A/C clutch.
Air Conditioning Cycling Switch (ACCS): A sensor, signal, or circuit which indicates status of the A/C cycling switch.
Air Conditioning Demand (ACD): A sensor, signal, or circuit which indicates status of the A/C demand switch.
Air Conditioning On (ACON): A sensor, signal, or circuit which indicates status of the A/C system.
Air Conditioning Pressure (ACP): A sensor, signal, or circuit which indicates pressure in the A/C system.
Air Conditioning Pressure Switch (ACPSW): A switch used for additional A/C system pressure control. Also referred to as the refrigerant containment/fan function switch.
AIR: Secondary Air Injection.
AIRB: Secondary Air Injection Bypass. AKA TAB
AIRD: Secondary Air Injection Diverter. AKA TAD
Air/Fuel Ratio: Air to fuel mixture ratio; 14.7:1 is also called stoichiometry. This value is monitored & stored by the PCM as the LAMBSE PID.
ALVW: Adjusted Loaded Vehicle Weight, defined by (Curb Weight + GVWR) /2.
Ambient Temperature: Temperature of the air surrounding an object.
Analog: 1. An electrical signal that can attain any value within the voltage limits of the signal, OR a mechanical display capable of any intermediate value. Contrast Digital 2. A substitue or simulation that functions similarly to the actual item.
Analog Meter: A handheld tool with an analog (needle) display for measuring various characteristics of electrical/electronic circuits & components. Contrast DMM.
Anti-lock Brake System (ABS): An electro-hydraulic system which prevents wheel lockup during an emergency stop by modulating brake pressure. Allows the driver to maintain steering control and stop the vehicle in the shortest possible distance under most conditions. Several versions exist including RABS, RABS-II, 3-channel 4WABS, 4-channel 4WABS, TA, & TC.
AOD: Automatic Overdrive transmission. Predecessor to AODE, 4R70W, 4R44E, 4R55E.
AODE: Automatic Overdrive Electronic transmission.
ARB: An aftermarket manufacturer of bumpers & a pneumatic selectable-locking differential. See "What's the DIFF?" Compare E-Locker.
ARC: Automatic Ride Control.
ASCII: American Standard Code for Information Interchange; a standardized digital binary code of letters, numbers, & symbols.
ATDC: After Top Dead Center; a time or angle of a given crankshaft lobe (usually #1) just after it has aligned with its connecting rod, and the piston is moving toward the crankshaft.
Automatic Ride Control (ARC): A system that automatically adjusts the suspension system to accommodate varying road and driving conditions.
Averaging Bank/Trade: Used for Nox Credits on Heavy Duty Trucks Only.
AWD: All Wheel Drive. A powertrain system which delivers engine power through a differential in the transfer case to differentials in each axle. Contrast RWD, FWD, 4WD.
AX4N: Automatic 4 speed Non-synchronous transaxle.
AX4S: Automatic 4-speed Synchronous transaxle.
B+: Battery Positive Voltage.
BARO: Barometric Pressure.
Barometric Pressure (BARO): A sensor, signal, or circuit which indicates the pressure of the surrounding air at any given temperature and altitude. See MAP.
Base Idle: Idle rpm determined by the throttle lever hardset on the throttle body with the IAC solenoid disconnected. It is preset at the factory & should never be adjusted.
Base Timing: Spark advance in degrees before top dead center of the base engine without any control from the PCM or ICM (EFI), or any vacuum- or centrifugal advance (carb).
Battery: An electrical storage device designed to produce a DC voltage by means of an electrochemical reaction. Common automotive batteries develop ~13.2VDC using lead & sulfuric acid, with the negative (-) terminal grounded to the chassis, body, & engine.
Battery Positive Voltage (B+): The positive voltage from the battery or any circuit connected directly to the battery, relative to chassis ground. Compare "Vehicle Power (VPWR)."
BATTEMP: Battery Temperature.
BBL: Barrel (carburetor/vacuum). Compare Venturi.
BI: fuel code for Other Bi-Fuel
Bigblock: An engine family of varying displacements that share some parts & characteristics, most of which have higher displacement than most of those in another family of engines from the same manufacturer. Contrast Smallblock, Short Block, Long Block.
Billet: A dense form of metal (usually Aluminum) made by mechanically compressing a cast ingot to eliminate any internal pores, and then re-heating it to relieve internal stress & re-crystallize it.
Binary: a simple numbering system using only two possible characters (usually 0 & 1) in each digit. "Bi-" means two. The binary representation of one is "1"; two is "10"; three is "11"; nine is "1001"; fourteen is "1110".
BJB: Battery Junction Box.
Blinker Fluid: A joke among mechanics & gearheads to detect amateurs. See KaleCo Automotive.
Blower (BLR): A device designed to supply a current of air at a moderate pressure. A blower usually consists of an impeller assembly, a motor and a suitable case. The blower case is designed as part of the ventilation system.
BLR: Blower.
BOO: Brake On/Off.
BPA: Bypass Air.
BPA-ISC: Bypass Air Idle Speed Control solenoid. Compare IAC.
BPP: Brake Pedal Position.
Brake On/Off (BOO): A switch which indicates the position of the brake pedal &/or activates the brake lights. It may also perform other functions. Compare BPP, Stop Lamp Switch.
Brake Pedal Position (BPP): A sensor, signal, or circuit which indicates the position of the brake pedal for use by the traction control &/or restraint systems. Compare BOO.
Breakout Box: A service tool that "tees" between the PCM and the matching harness connector. The breakout box contains test pins that can be probed for EEC system testing without the risk of damage to the EEC, its wiring, or its connector by direct probing.
BTDC: Before Top Dead Center; a time or angle of a given crankshaft lobe (usually #1) just before it has aligned with its connecting rod, and the piston is approaching its maximum distance from the crankshaft. Ignition spark usually occurs during this phase.
Bus+ or -: Bus positive or negative.
Bus positive or negative (Bus+ or -): Circuits that carry data to & from the various modules on a network, & the DLC.
BV - Bowl Vent (carburetor/vacuum)
BW 1342: A rare chain-driven 4WD (no internal differential) part-time 2-speed transfer case built by Borg-Warner with a fixed front yoke output on the L side. It replaced the NP 208F for a few years in heavy-duty light trucks until it was replaced by the 1356, and was always built with a fixed rear output yoke.
BW 1356: A common chain-driven 4WD (no internal differential) part-time 2-speed transfer case built by Borg-Warner with a fixed front yoke output on the L side & a magnesium-alloy case. It replaced the NP 208F & BW 1342, and was built in several configurations: manual-shift/ESOF; with/without PTO (Aluminum front case); with/without speedo gear bore; fixed/slip rear output; yoke/companion flange rear output.
Bypass Air (BPA): Mechanical control of throttle bypass air. Compare IAC.
Cab: The cabin of a truck or a piece of equipment.
Cabin: The operator & passenger compartment(s) of a vehicle or piece of equipment. Except for unibody, distinguished from the chassis, cargo area, & accessory attachments.
CAC: Charge Air Cooler. See Intercooler.
CAFE: Corporate Average Fuel Economy. A set of federal requirements and regulations which stipulate fuel economy standards based on a manufacturer's entire production output.
Camshaft: A shaft on which phased cams are mounted or cast. The camshaft is used to regulate the opening and closing of the intake and exhaust valves.
Camshaft Position (CMP): A sensor, signal, or circuit which indicates camshaft position.
Canister: A device designed to hold dry material. An evaporative emission canister contains activated charcoal (carbon) which absorbs fuel vapors and holds them until they can be purged into the intake at an appropriate time.
CANP: Canister Purge.
Canister Purge (CANP): A solenoid valve, or the signal or circuit which controls it, to purge the carbon canister. Compare VMV.
CANV: Canister Vent.
Canister Vent (CV, CANV): A solenoid valve, or the signal or circuit which controls it, to allow fresh air into the carbon canister.
CARB: California Air Resource Board; a government agency which sets & enforces emissions standards within California, and issues certifications of compliance to aftermarket parts.
Carbon Fiber: A fiber material formed by (essentially) burning plastic (acrylic) fibers in a deoxygenated kiln, resulting in microscopic tubes of graphite. These fibers can then be used to reinforce resins, in the same way fiberglass or Kevlar are. Carbon fiber is between fiberglass & Kevlar both in strength and price, but can be made higher in rigidity than either. In some applications, it is woven into sheets & embedded in a transparent resin, resulting in a distinctive pattern that is often imitated purely for cosmetic & marketing purposes.
Cardone: a parts company.
Cardan joint: a type of universal joint consiting primarily of a right-angled cross (aka Hooke's joint & Hardy-Spicer joint). See Double Cardan Joint.
Case Ground (CSE GND): The dedicated circuit from the PCM case to chassis ground.
Castellated Nut or Castle Nut: A nut with slots cut across one face to allow a cotter pin to lock it, commonly used on suspension studs & bolts.
Catalyst: A material which facilitates or accelerates a chemical reaction without being consumed. See also Catalytic converter.
Catalytic Convertor: An in-line, exhaust system device used to reduce the level of engine exhaust emissions. AKA Thermactor.
CCD: Computer Controlled Dwell; Charge Coupled Device (a digital image sensor).
CCRM: Constant Control Relay Module.
CCS: Coast Clutch Solenoid.
CD: fuel code for Bi-Fuel, CNG/Diesel
CD4E: CD class vehicle, 4 speed, Electronic transmission.
CEL: Check Engine Light. See MIL.
Central Point Injection (CPI): A fuel-delivery system in which fuel is delivered to the throttle body to be distributed through the intake manifold to the cylinders.
Chassis: The basic structure of a vehicle, including the suspension & any components that position the suspension. These may include the frame, subframes, unibody, struts, springs, shocks, axles, A-arms, radius arms, watts links, antisway bars, tires, rims, brakes, & bumpers. The powertrain is sometimes considered part of the chassis. Distinguished from the body (except unibody), cabin, interior, & accessories.
CHT: Cylinder Head Temperature.
CI: Cylinder Injection; Cubic Inch displacement
CID: Cylinder Identification.
Circuit: A complete electrical path or channel, usually includes the source of electrical energy. Circuit may also describe the electrical path between two or more components. May also be used with fluids, air or liquids.
CKP: Crankshaft Position.
Clock Spring: A thin coiled (like a clock spring) plastic ribbon containing lines of metal used to electrically connect a rotating object (usually a steering wheel) to a non-rotating object (the steering column). Although a clock spring provides a more stable connection (for airbags) than the older sliding contacts (used for horns & cruise control), it is less reliable over time. The traces of metal often crack, resulting in a failed open circuit.
Clutch: A mechanical device which uses mechanical, magnetic or friction type connections to facilitate engaging or disengaging of two shafts or rotating members.
Clutch Pedal Position (CPP): A sensor, signal, or circuit which indicates clutch pedal position.
CMP: Camshaft Position.
CMS: Catalyst Monitor Sensor. AKA Downstream HO2S; B1S2 & B2S2.
CMVSS: Canadian Motor Vehicle Safety Standards.
CNG: Compressed Natural Gas. See Natural Gas.
CO: Carbon Monoxide; a colorless, odorless gas that displaces oxygen and bonds to red blood cells, causing unconsciousness & death. It is produced from incomplete (rich) combustion.
CO2: Carbon Dioxide; a colorless, slightly acidic gas produced by combustion & respiration that dissolves easily in water. High concentrations cause difficulty breathing & disorientation.
Coast Clutch Solenoid (CCS): Controls the application and release of the coast clutch in the transmission.
Coil: 1. A device consisting of windings of conductors around an iron core, designed to increase the voltage and for use in a spark ignition system; 2. A type of spring constructed as a twisted bar of steel. Its rate is closer to constant over a longer travel than most other types of spring.
Cold Soak: Time given to a vehicle to sit at a low temperature (typically below 68° F / 20° C) until the temperature of external and internal components stabilize.
Companion Flange: A 2-piece connection between a splined shaft & a U-joint in a driveshaft. One piece is a splined disk with a centering hub & several threaded holes for bolts. The other piece captures the caps of the U-joint and bolts to the face of the disk. It is faster to assemble than a yoke, and allows easier adjustment for driveshaft balance.
Compression: A measurement of a cylinder's ability to develop pressure. Although measured in PSIg, the actual number is not significant. Rather the relationship of each cylinder to the others in that engine defines Pass/Fail in a compression test. Actual pressure can vary due to engine temperature, ambient temperature & elevation, engine wear, oil viscosity, & even time since the engine last ran.
Computed Timing: The total spark advance in degrees before top dead center. Equals base timing plus/minus an additional factor calculated by the PCM based on input from a number of sensors.
Connector: A device which holds electrical terminals or other ducts in contact so that flow is maintained, generally made of plastic. Electrical connectors generally hold several pairs of terminals and are only necessary during vehicle assembly. Fuel Line Connectors are sometimes metal, and some require special tools & procedures to separate.
Constant Control Relay Module (CCRM): A relay module that provides on-off control of various EEC components.
Convertible: A vehicle body designed to be re-configured by the operator, usually by removing or collapsing the roof or a section of the roof.
Continuous Memory: The portion of KAM used to store DTCs generated during Continuous Memory Self-Test.
Continuous Memory Self-Test: A continuous test of the EEC system conducted by the PCM whenever the vehicle is operating.
Control: A means or a device to direct and regulate a process or guide the operation of a machine, apparatus or system.
Coolant: A fluid used for heat transfer. Coolants usually contain additives such as rust inhibitors, bittering agents, and ethylene glycol (a sweet-tasting but poisonous antifreeze/antiboil agent).
COP: Coil On Plug Integrated EI System. See Electronic Ignition System.
Coupe: An enclosed passenger vehicle with 2 doors & a rigid roof structure.
CPI: Central Point Injection. AKA TBI
CPP: Clutch Pedal Position Switch. Located on the clutch pedal and detects when the clutch pedal is depressed.
CQIS: Common Quality Indicator System.
Crankcase: The enclosed mechanical chambers of an engine which contain lubricating oil & blowby gases, including water, fuel vapor, & soot. Contrast Block. See PCV.
Crankshaft: The part of an engine which converts the reciprocating motion of the pistons to rotary motion.
Crankshaft Position (CKP): A sensor, signal, or circuit which indicates crankshaft position.
Cross-drilled Rotor: A disk brake rotor which has had holes drilled through both surfaces in a pattern which maintains balance. The purpose is to remove weight from a brake rotor which is larger than necessary for the vehicle. This results from unusually large wheels found on race vehicles, which allow the designer to specify larger rotors. The benefits include: less pedal force; less hydraulic pressure; and less load on the pads & their mountings to achieve the same braking force; all of which allow those components to be lighter. The disadvantage is the higher unsprung weight of the large rotor, and the higher momentum of the spinning tire/rotor assembly. But cross-drilling overcomes both of these by removing unnecessary weight. Because the rotor is oversized to begin with, the loss of some of the friction surfaces is insignificant for light race vehicles. However, removing metal from the disk's surface causes the pads & rotors to wear faster, and causes heat to build up to higher temperatures. Neither of those factors are concerns on race vehicles, but on typical production vehicles, they are. Cross-drilling on street vehicles is cosmetic, and counterproductive to braking efficiency. See Slotted Rotor, Wilwood FAQ.
Crumple Zone: An area of a chassis OUTside the cabin designed to bear all normal loads, but weak enough to collapse during a collision, allowing more time for the occupants to accelerate (change speed or direction) so they are less likely to come in contact with the cabin. Certain aftermarket equipment (mainly bumpers, brush guards, & trailer hitches) can interfere with this function, causing restraint systems to fail. AKA Accordion.
CSE GND: Case Ground.
CT: Closed Throttle Mode.Curb Idle: PCM controlled idle rpm.
CTO: Clean Tach Output. Signal used to drive the instrument panel tachometer.
Curb Weight: The actual weight of a regular-production vehicle fully ready to be operated normally, including all fluids & factory-installed optional equipment; but no occupants, cargo, or accessories. Contrast GVW, GVWR.
CV: Canister Vent; Constant Velocity.
Cylinder Head Temperature: A sensor, signal, or circuit which indicates the DRY temperature of the engine cylinder head. Contrast ECT & coolant temperature sender; both of which are immersed in engine coolant.
Cylinder Identification (CID): A signal or circuit which provides crankshaft or camshaft position information for fuel injection synchronization.
D: combustion code for Diesel Cycle
D: fuel code for Diesel
Data: General term for information, usually represented by numbers, letters, or symbols.
Data Link Connector (DLC): Connector providing access and/or control of the vehicle information, operating conditions, and diagnostic information.
Data Output Line (DOL): A circuit that sends certain information from the PCM to the instrument cluster.
Data Positive or Negative (DATA+ or DATA-): Circuits that carry data to the DLC, Message Center, or VCRM.
DATA+ or DATA-: Data Positive or Negative.
Daytime Running Lamps (DRL): A system that keeps the vehicle headlamps on at all times (though often at reduced power & without marker lamps) while the vehicle is operating.
DC: Direct Current. Electric current flowing in one direction.
DC: Duty Cycle. The ratio of ON time versus the full cycle period, expressed in percent.
DCL: Data Communication Link. See DLC.
Decimal: a common numbering system using ten possible characters in each digit, based on human fingers. "Deci-" means ten.
DEF: Defroster.
Defroster (DEF): An electrically heated device designed to remove ice, frost or snow from the rear window of the vehicle.
Detonation: See Knock.
Detroit Locker: An aftermarket locking differential famous for reliability & robustness. See "What's the DIFF?"
DI: Distributor Ignition.
DI: Direct Injection (diesel).
DLC: Data Link Connector. J1962 or EEC-IV connector providing access to vehicle diagnostic information.
Diagnostic Test Mode (DTM): A level of capability in an On-Board Diagnostic (OBD) system. This may include different functional states to observe signals, a base level to read Diagnostic Trouble Codes, a monitor level which includes information on signal levels, bi-directional control with on/off board aids, and the ability to interface with remote diagnosis.
Diagnostic Trouble Code (DTC): An alpha/numeric identifier for a fault condition identified by the On-Board Diagnostic System.
Diesel: 1. A german scientist who invented a simple & reliable engine which can run efficiently on very low-grade fuel oil; 2. An engine which operates on the Diesel (2-stroke or 4-stroke) cycle; 3. The fuel for such engines. Untaxed diesel fuel (for agricultural use) in the US has a dye added so that inspectors can tell if it was used in taxable vehicles.
Dieseling: See Knock.
Differential: A mechanism for dividing the engine's power between 2 shafts, most often between the 2 axleshafts within an axle or transaxle, but also sometimes between 2 driveshafts within an AWD transfer case. See "What's the DIFF?" Contrast Spool, Lincoln-Locker, 4WD.
Differential Pressure: The pressure difference between two regions, such as between the intake manifold and the atmospheric pressures.
Differential Pressure Feedback EGR (DPFE): An EGR system or its primary sensor that monitors EGR pressure across a remote orifice to control EGR flow. AKA Dual Pressure Feedback EGR
Digital (Electrical/Electronic): An electrical signal that is stepped among certain possible values within the voltage limits of the signal; OR a display capable of only certain preset values/elements; OR controls which process information by switching the current or voltage ON and OFF. Contrast Analog.
Digital MultiMeter (DMM): A handheld tool with a digital display for measuring various characteristics of electrical/electronic circuits & components. Digital meters require less current from the circuit being tested and produce more accurate & precise readings. They also generally have more features and cost far less than older meters. Contrast Analog Meter.
Digital Transmission Range sensor (DTR or TR): A sensor, signal, or circuit which indicates the selected modes of the transmission. It may be used for PCM control of shifting, cruise &/or starter interrupt. AKA MLP, MLPS, PNP, NSS.
Digital Volt-Ohm Meter (DVOM): A handheld tool with a digital display for measuring voltage or resistance characteristics of electrical/electronic circuits & components. See DMM.
Direct Injection (DI): A diesel cylinder head design in which the fuel injector pintle is within the combustion chamber.
Direct-Replacement: Parts engineered to be exactly equivalent to OE parts, but produced by non-OEM.
Disk Brakes: A braking system based on a 2-sided brake rotor with a pad wearing against each side. The pads are compressed against the rotor by a caliper (usually hydraulic), creating a braking force on the rotating hub. They are less complex than drum brakes, and are less affected by extended use, fording, or high speed. See also Cross-drilled Rotor, Slotted Rotor, Drum-in-Hat. Contrast Drum Brakes.
Distributor: A mechanical device designed to switch a high voltage secondary circuit from an ignition coil to spark plugs in the proper firing sequence.
Distributor Ignition (DI): A system in which the ignition coil secondary circuit is switched by a distributor in proper sequence to various spark plugs.
DLC: Data Link Connector.
DM: fuel code for Bi-Fuel, Diesel/Methanol
DMM: Digital MultiMeter. Compare DVOM. Contrast Analog Meter.
DOHC: Dual Overhead Cam.
DOL: Data Output Line.
Door Jamb Sticker: See Safety Certification Label.
DOT: Department of Transportation. A federal office which oversees (among MANY other things) roads & motor vehicles.
Double Cardan joint: an assembly of 2 cross-type U-joints linked by a very short coupling with a mechanism between them to hold the coupling at exactly 1/2 the total flex angle across the assembly. It provides near-constant angular velocity through the joint, and allows nearly double the flex angle of a single cardan joint.
DPFE or DPFEGR: Differential (Dual) Pressure Feedback EGR. Compare PFE.
DRI: Deposit Resistant Injector. A fuel injector designed to prevent buildup of carbon and other unwanted deposits used since the mid-80s.
Drilled Rotor: See Cross-drilled Rotor.
Driveshaft: A shaft connecting a transmission or transfer case to an axle or differential. It is usually tubular, either steel, Aluminum, Aluminum-Metal Matrix (AMMX), or composite. It usually includes at least 1 U-joint, CV joint, or rubber coupling disk at each end, & a slip joint (to allow for compression & extension). For longer distances, an intermediate joint & carrier bearing may be used.
DRL: Daytime Running Lamps.
Drum Brakes: A braking system based on a wide cast-iron hoop with a thin plate on one side surrounding 1 or 2 shoes covered in friction material, which are themselves attached to a large plate on the suspension (usually a solid axle), enclosing the entire mechanism. The shoes are spread against the hoop's inner surface either by a hydraulic slave (wheel) cylinder, or by a scissor mechanism, or by a lever mechanism, and usually also by an adjusting mechanism (usually automatic). See also Drum-in-Hat. Contrast Disk Brakes.
Drum-in-Hat: A brake system combining a small drum brake (usually only for emergency/parking use) inside the rotor of a disk brake (usually on the rear axle). See Disk Brakes, Drum Brakes.
DTC: Diagnostic Trouble Code.
DTM: Diagnostic Test Mode.
DTR: Digital Transmission Range sensor.
Dual Overhead Cam (DOHC): An engine configuration that uses two camshafts in each cylinder head, positioned above the valves.
Duckbill: The common term for a specific style of plastic clip used on some fuel line fittings, especially fuel filters. Compare Garter Spring.
Dust Cap: The outboard cover for a hub. Some include the knob or dial for manual hub locks on 4WD vehicles.
DVOM: Digital Volt-Ohm Meter. Compare DMM.
E4OD: Electronic 4-speed Overdrive automatic transmission. Renamed 4R100; one of the strongest, longest, & heaviest automatic transmissions ever put in a light truck. Models built before 1995 developed a poor reputation.
E: combustion code for Electric
E: fuel code for Ethanol
E85: Fuel containing 85% ethanol alcohol. Pure ethanol is the alcohol which is the intoxicating agent in liquor, beer and wine. It is distilled from the fermentation of plants such as field corn and sugar cane. A denaturant that imparts a bad taste is added to ethanol to preclude consumption. Up to 5% hydrocarbons (such as unleaded gasoline) is a typical denaturant. The resulting denatured ethanol is designated Ed100 when used as a feedstock for motor fuels. Fuel ethanol (Ed85) is then made by adding 15% more unleaded gasoline. The resulting fuel also has a higher octane rating than unleaded regular gasoline, allowing engine designs with higher compression and corresponding greater engine efficiency and performance (power). Winter blends may contain up to 25% unleaded gasoline (plus the denaturant) to enhance cold engine starts, hence the sometimes used Ed85-Ed75 designation. Severely cold weather may require additional measures for reliable starting. Ethanol is more chemically active than gasoline. It corrodes some metals and may cause some plastic and rubber components to swell, break down, or become brittle and crack, especially when mixed with gasoline. Special materials and procedures are used with Ethanol FFVs. Ethanol has less energy per gallon than gasoline, so fuel economy in miles per gallon will decrease as the percentage of ethanol goes up. However, the decrease is not as severe as with methanol. Flexible fuel vehicles using fuel ethanol also have lower exhaust emissions than comparable gasoline vehicles.
EAIR: Electric Secondary Air Injection.
EAP: Electric Air Pump.
ECT: Engine Coolant Temperature.
EEC: Electronic Engine Control.
EEC-IV: Ford's fourth generation EEC system; its first to incorporate on-board diagnostics (OBD) & memory to store diagnostic trouble codes (DTCs). Their chips are soldered to their boards (meaning they can't be removed to change performance characteristics like some other manufacturers), but later versions include flash-programmable memory (EEPROM).
EEC-V: Ford's fifth generation EEC system, which incorporates the industry-standard OBD-II system.
EEPROM: Flash Electrically Erasable Programmable Read Only Memory.
EFT: Engine fuel temperature.
EGR: Exhaust Gas Recirculation.
EGRT: EGR Valve Temperature Sensor.
EGR Vacuum Regulator (EVR): A solenoid vacuum valve which controls vacuum to the EGR valve by a duty cycle (pulse) signal from the PCM. This, in turn, regulates EGR flow into the intake manifold.
EI: Electronic Ignition.
Electric Air Pump (EAP): An electric pump used in EAIR systems.
Electronic Engine Control (EEC): The system that provides electronic control of engine (and often transmission) operation.
Electronic Ignition (EI): A system in which the ignition coil secondary circuit is dedicated to specific spark plugs without the use of a distributor. Ford has two types of EI systems, integrated EI and EI. EI is only used on the 3.0L Windstar and has a standalone Ignition Control Module (ICM). The Integrated Electronic Ignition (EI) System consists of a crankshaft position (CKP) sensor, coil pack(s), connecting wiring, and PCM. The Coil On Plug (COP) Integrated EI System uses a separate coil for each spark plug and each coil is mounted directly onto the plug. The COP Integrated EI System eliminates the need for spark plug wires but does require input from the camshaft position (CMP) sensor.
Electronic Pressure Control (EPC): An actuator, signal, or circuit which controls line pressure in the transmission.
Electric Secondary Air Injection (EAIR): A pump-driven system for providing secondary air using an electric air pump.
Electronic Shift-On-the-Fly (ESOF): A system used to operate the transfer case of a 4WD or AWD vehicle while it is in motion.
EMI: Electromagnetic Interference. Usually caused by ignition voltage spikes, solenoids, relay operation or noisy generator contacts.
Electronic Variable Orifice Steering (EVO): A system or solenoid valve which adjusts the level of assistance provided by the power steering system.
E-Locker: An aftermarket electronically-selectable-locking differential produced by Eaton. See "What's the DIFF?"
Engine: A machine designed to convert thermal energy (typically derived from chemical energy in fuel) into mechanical energy to produce force or motion.
Engine Coolant Temperature (ECT): A sensor, signal, or circuit which indicates the temperature of the engine coolant. It is typically installed in the heater core circuit, which is unaffected by the thermostat.
Engine Fuel Temperature (EFT): A sensor, signal, or circuit which indicates the temperature of the fuel in the fuel rail.
Engine RPM (RPM): A signal or circuit which indicates engine rpm.
Engine RPM/Vehicle Speed Limiter: A strategy to prevent damage to the powertrain. The powertrain control module (PCM) will disable some or all of the fuel injectors whenever an engine rpm or vehicle overspeed condition is detected. The vehicle will exhibit a rough running engine condition, and the PCM will store a Continuous Memory DTC P1270. Once the operator reduces the excessive speed, the engine will return to the normal operating mode. No repair is required. However, the technician should clear the PCM and inform the operator of the reason for the DTC. Excessive wheel slippage may be caused by sand, gravel, rain, mud, snow, ice, etc. or excessive and sudden increase in rpm while in NEUTRAL or while driving.
EOL: End Of Line. A system designed specifically for use at assembly plants to make sure all new vehicles perform to design specifications.
EPA: Environmental Protection Agency; a government agency which sets & enforces emissions standards in the US.
EPC: Electronic Pressure Control.
ESOF: Electronic Shift-On-the-Fly.
Ethanol: Grain alcohol; C2H5OH. An inexpensive fuel additive used to reduce cost and emissions. Blends containing more than ~15% ethanol require special engine management & fuel system materials. See E85.
Ethylene Glycol: The most common antifreeze/antiboil agent in automotive coolant. It tastes sweet, but is extremely poisonous; attaching to the liver, it prevents normal toxins from being removed from the blood.
EVAP: Evaporative Emission system.
Evaporative Emission (EVAP): A system to prevent fuel or other hydrocarbon vapors from escaping into the atmosphere. Typically includes a charcoal canister to store fuel vapors, a rollover valve on the fuel tank to prevent liquid fuel from entering the system, various airflow control solenoid valves, & the PCV system.
EVO: Electronic Variable Orifice.
EVR: EGR Vacuum Regulator.
EWP: Electric Water Pump.
Exciter Ring: See Tone Ring.
EXH HCV - Exhaust Heat Control Valve (carburetor/vacuum)
Exhaust Gas Recirculation (EGR): A system which reduces NOx emissions levels by adding exhaust gas to the incoming air/fuel mixture, OR the valve used to regulate the flow of exhaust gas. The inert gas reduces combustion chamber temperatures, which not only reduce the formation of NOx, but also reduces the tendency to burn through Aluminum/alloy pistons.
Exo-Cage: An external cage designed to protect a vehicle's body when off-roading. Most are primarily cosmetic, and not actually strong enough to work in an off-road rollover or on-road collision. Contrast Step Bar; Nerf Bar; Rock Slider.
F4E: F Level (119 lb-ft) 4 speed Electronic transmission.
Fail-Safe Cooling Strategy (FSC): A strategy activated by the PCM only in the event that an overheating condition has been identified. This strategy provides engine temperature control when the cylinder head temperature exceeds certain limits. The cylinder head temperature is measured by the CHT sensor. Not all vehicles equipped with a CHT sensor will have the fail-safe cooling strategy. A cooling system failure such as low coolant, electric cooling fan failure, or coolant loss could cause an overheating condition. As a result, damage to major engine components could occur. Along with a CHT sensor, the fail-safe cooling strategy is used to prevent damage by allowing air cooling of the engine. This strategy allows the vehicle to be driven safely for a short time with some loss of performance when a overheat condition exist. Engine temperature is controlled by varying and alternating the number of disabled fuel injectors. This allows all cylinders to cool. When the fuel injectors are disabled, their respective cylinders work as air pumps, and this air is used to cool the cylinders. The more fuel injectors that are disabled, the cooler the engine runs, but the engine has less power. A wide open throttle (WOT) delay is incorporated if the CHT temperature is exceeded during WOT operation. At WOT, the injectors will function for a limited amount of time allowing the customer to complete a passing maneuver. Before injectors are disabled, the fail-safe cooling strategy alerts the operator to a cooling system problem by moving the instrument cluster temperature gauge to the hot zone and a PCM DTC P1285 is set. Depending on the vehicle, other indicators, such as an audible chime or warning lamp, can be used to alert the operator of fail-safe cooling. If overheating continues, the strategy begins to disable the fuel injectors, a DTC P1299 is stored in the PCM memory, and a malfunction indicator light (MIL) (either CHECK ENGINE or SERVICE ENGINE SOON), comes on. If the overheating condition continues and a critical temperature is reached, all fuel injectors are turned off and the engine is disabled.
Failure Mode Effects Management (FMEM): An alternative vehicle operation strategy that protects vehicle function from the adverse effect of an EEC system failure.
Fan: A device designed to supply a current of air. A fan may also have a frame, motor, wiring harness and the like.
Fan Control (FC): A sensor, signal, or circuit for controlling the engine cooling fan.
Fender: The body panel above the front wheel.
FC: Fan Control.
FEAD: Front End Accessory Drive belt system.
FEPS: Flash EEPROM Programming Signal. 18 volt DC signal sent by the scan tool to initiate PCM reprogramming.
FF: Flexible fuel.
FFV: Flexible Fuel Vehicle.
FIFO: First In First Out.
FILO: First In Last Out.
Firewall: The body panel between the engine bay & the passenger compartment.
Fixed Yoke/Flange: A non-moving connection between a splined shaft (usually the output shaft of a transmission or transfer case) and a U-joint in a driveshaft. Broncos use a fixed yoke or flange on the t-case rear output.
Flash Electrically Erasable Programmable Read Only Memory (EEPROM): An Integrated Circuit (IC) within the PCM. This IC contains the software code required by the PCM to control the powertrain. One feature of the EEPROM is that it can be electrically erased and then reprogrammed without removing the PCM from the vehicle. If a software change is required to the PCM, the module no longer needs to be replaced, but can be reprogrammed at the dealership through the DLC.
Flat-Rate: A common pay plan for automotive technicians, especially at a dealership. A comprehensive list of possible vehicle repairs is published (either by the manufacturer in the case of dealership & warranty repairs or technicians, OR by a 3rd-part company in the case of independent techs & customer-pay repairs) with specific descriptions of the taks involved and the typical or allowable time to accomplish those tasks. Regardless of how long it actually takes the technician to complete the repair or the total cost billed to the vehicle owner, the tech is only paid for the published time. AKA "book time". Contrast "straight time" or "clock time".
Flexible Fuel (FF): A system capable of using a variety of fuels for vehicle operation. These may include gasoline, diesel, biodiesel, ethanol, methanol, natural gas, propane, jet fuel, solar, or any combination.
FLTR - Filter (carburetor/vacuum)
Fluorescent: The physical characteristic of a substance by which it converts absorbed radiation at one frequency (usually invisible) into a visible-frequency radiation (light). Most commonly, a mercury-vapor tube generates UV radiation, which is fluoresced into white light by the powdered phosphor coating inside the tube.
FMEM: Failure Mode Effects Management.
Forced Induction: Any air intake system using mechanical devices to push air into the intake at higher-than-atmospheric pressure. Contrast N/A. See Turbocharger, Supercharger, Ram-Air.
Four Valve (4V): Four valves, two intake and two exhaust, per cylinder.
FP: Fuel Pump.
FPDM: Fuel Pump Driver Module.
FPM: Fuel Pump Monitor.
FPR: Fuel Pressure Regulator.
FPRC: Fuel Pressure Regulator Control.
Frame: The heavy structure to which all other major components of a cab-on-chassis vehicle are attached. Common types include ladder & monocoque. Contrast Unibody.
Frame Horn: The end of a frame rail where something may be attached, such as a bumper.
Front End Accessory Drive (FEAD): A system of belts & pullies on the engine to transfer power from the crankshaft to various accessory devices.
Freeze Frame: A block of memory containing the vehicle operating conditions for a specific time. Typically associated with a DTC.
FSA: Field Service Action. See Recall.
FSC: Fail-Safe Cooling Strategy.
FTP: Fuel Tank Pressure.
Fuel: Any combustible substance burned to provide heat or power. Typical fuels include gasoline and diesel fuel. Other types of fuel include ethanol, methanol, natural gas, propane or any combination.
Fuel Injector: See Injector.
Fuel Pressure Regulator (FPR): A vacuum-operated valve on or near the fuel manifold (rail) which regulates fuel pressure from the pump to the injectors.
Fuel Pressure Regulator Control (FPRC): A sensor, signal, or circuit which controls the fuel pressure regulator. Used primarily to provide extra fuel during cold starts.
Fuel Pump (FP): A pump used to deliver fuel to the engine, usually submerged in the fuel tank.
Fuel Pump Driver Module (FPDM): A module that controls an electric fuel pump in response to a pulse-code modulated (PCM) signal from the EEC.
Fuel Pump Monitor (FPM): A sensor, signal, or circuit which monitors operation of the fuel pump.
Fuel Rich/Lean: A qualitative evaluation of air/fuel ratio relative to an ideal A/F ratio known as stoichiometry, or 14.7:1 for normal gasoline. In the EEC system, rich/lean is determined by a voltage signal from the HO2S. An excess of oxygen (lean) is indicated by an HO2S voltage of less than .4 volts; a rich condition is indicated by an HO2S voltage of greater than .6 volts.
Fuel Tank Pressure (FTP): A sensor, signal, or circuit which indicates the internal pressure of the fuel tank and the EVAP system.
Full-Floating Axle: An axle assembly whose axleshafts bear no weight, and can therefore "float" within the housing. Because the shafts only experience torsional stresses, it is considered stronger (less likely to break) than a Semi-Floating Axle. All steering axles are full-floating. Most Portal Axles are full-floating, but their outers can be semi-floating.
FWD: Front Wheel Drive. A powertrain system which delivers engine power to a differential in the front axle only. Contrast RWD, AWD, 4WD.
G: fuel code for Gasoline
Garter Spring: A style of quick connection used on some fuel or A/C line fittings. Contrast Duckbill.
GE: fuel code for Bi-Fuel, Gasoline/Ethanol.
GEM: Generic Electronic Module.
GEN: Generator.
Generator (GEN): A rotating machine designed to convert mechanical energy into electrical energy. AKA Alternator (a term copyrighted by Chrysler Corporation).
GM: fuel code for Bi-Fuel, Gasoline/Methanol. Also, Grand Marquis, General Motors Corporation.
GND: Ground.
Gold Plated Pins: Some engine control hardware has gold plated pins on the connectors and mating harness connectors to improve electrical stability for low-current circuits and to enhance corrosion resistance. The EEC components equipped with gold terminals will vary by vehicle application. Damaged gold terminals should only be replaced with new gold terminals.
Goose: A brief opening and closing of the throttle (Dynamic Response test).
Gov-Lock: An OE torque-biasing differential offered in GM trucks. It is very effective, but very delicate and has a history of exploding when overrevved. See "What's the DIFF?"
GPM: Grams Per Mile; Gallons Per Minute.
GPS: Global Positioning System. A network of geostationary satellites, or a device used to monitor signals from those satellites, and calculate its own position from that data.
Grade: A categorization of strength, toughness, & durability of fasteners. AKA Material Class in metric fasteners.
Green State Vehicle: Formally known as California Emissions. A vehicle that is equipped with California on-board diagnostics.
Ground (GND): An electrical conductor used as a common supply for electric circuits, and with a relative zero potential, generally connected to the (-) battery terminal. Electrons (which have a negative charge) flow out of this terminal, through the ground system, to electrical & electronic components which consume their energy, through fuses & control switches, and ultimately return to the battery (+) terminal. Some vehicles & accessories use a positive-ground wiring system.
Ground Plane: A flat physical surface (usually the ground or the metal body of a vehicle) directly under an antenna used to reflect radio waves to or from that antenna. It must be electrically grounded to the antenna to work. The concept is almost identical to a fluorescent tube standing upright on a black surface. Without a reflector at the bottom end, ~1/2 its output would strike the surface & be lost; but with a ground-plane reflector, that energy is redirected up & out, where it can be used. The term applies primarily to CB antennae on vehicles, where the lack of a physical ground plane on one side of the antenna (due to the antenna being installed on the side of the vehicle) results in poor transmission/reception range on the side of the antenna with no ground plane.
GVW: Gross Vehicle Weight. The maximum allowable curb weight of a vehicle.
GVWR: Gross Vehicle Weight Rating; GVW + cargo load.
H: combustion code for Hybrid Electric; chemical symbol for Hydrogen.
Hall Effect: A process where current is passed through a small slice of semi-conductor material at the same time as a magnetic field to produce a small voltage in the semi-conductor. Compare Magneto-Resistive sensor.
Halogen: A group of chemicals characterized by their ability to produce visible light when excited. They are often used in incandescent bulbs, but are also used in certain refrigerants for their other chemical characteristics.
Hard Fault: A fault currently detected by the system.
Hardware Limited Operating Strategy (HLOS): A mode of operation where the PCM replaces output commands with fixed values in response to certain PCM malfunctions.
HC: Hydrocarbon.
HDL: Headlamp.
Header or Header Pipe: An exhaust manifold fabricated from bent tubing (as opposed to being cast), usually tuned to maximize scavenging from the combustion chambers, resulting in more power from the engine. The tubes converge at the collector, which includes a fitting to attach the exhaust system. Some are wrapped or coated to keep heat in so that surrounding components are not damaged. Compare Shorty, Long-Tube Header.
Headlamp (HDL): Input that indicates status of the headlamps.
Heat Exchanger: Any device designed to transfer heat from one fluid to another, including the radiator, intercooler, heater core, & evaporator core.
Heat Riser Tube: A small duct that transfers warm air collected from around the exhaust manifold into the intake system (generally on carburetors before the filter) to aid in fuel vaporization in extreme cold weather.
HEAT VLV INT - Heat Valve Intake (carburetor/vacuum) regulates flow from the exhaust manifold shroud through the heat riser tube to the intake system.
Heated Exhaust Gas Oxygen sensor (HEGO): An Oxygen Sensor (O2S) that is electrically heated. AKA HO2S.
Heated Oxygen Sensor (HO2S): An Oxygen Sensor (O2S) that is electrically heated. AKA HEGO.
HEGO: Heated Exhaust Gas Oxygen sensor.
Hex or Hexadecimal: a rare numbering system using sixteen possible characters (usually 0-9 and A-F) in each digit. "Hexadeci-" means sixteen. Nine is "9"; ten is "A"; twelve is "C"; fifteen is "F"; sixteen is "10"; seventeen is "11"; thirty-one is "1F"; thirty-two is "20".
HFC: High Fan Control.
HFP: High Fuel Pump.
HHDE: Heavy Heavy Duty (gasoline, CNG, or FF) Engine.
HHDDE: Heavy Heavy Duty Diesel Engine.
HICV - Hot Idle Control Valve (carburetor/vacuum)
HID: High-Intensity Discharge.
High Fan Control (HFC): Controlling the high speed cooling fan.
High Fuel Pump (HFP): An output circuit or signal from the PCM which controls the high speed fuel pump.
High-Intensity Discharge (HID): A type of light bulb which uses high voltage to produce visible light in a manner similar to that of neon. They are much more efficient (less heat; lower current) than incandescent bulbs.
High Swirl Combustion (HSC): A cylinder and piston configuration that causes swirling of the air/fuel mixture in the cylinder.
HLOS: Hardware Limited Operating Strategy.
HO: High Output.
HO2S: Heated Oxygen Sensor.
Hot Soak: Period of time after an engine operates when its internal heat has not yet dissipated into the environment.
HSC: High Swirl Combustion.
Hub: The tubular rotating flange containing wheel bearings to which brakes & wheels are mounted.
Hub Lock: A mechanism for connecting a hub to an axleshaft, most often on the front suspension of a 4WD vehicle. They may be operated manually (the most common), pneumatically, electrically, mechanically, or automatically (the 2nd most common). Although some name-brand aftermarket manual hub locks have achieved an elevated status, they are all virtually indistinguishable based on quality, durability, & warranty. The only noticeable difference is in the ease of operation of the selector knob.
HydroBoost: A trademark name for a hydraulic brake booster. Contrast Vacuum Booster.
Hydrogen: A highly flammable gas. Chemical symbol H.
Hydrogen Generator: An aftermarket or homemade device usually consisting of a glass jar containing water and a heating element (usually INcorrectly referred to as an electrode) with a hose leading to the intake manifold. Proponents suggest that the bubbles coming off the element are pure Hydrogen, and that the energy it adds to the combustion chamber is greater than that required to generate the electricity consumed by the device, making it economical. There is no scientific basis for this belief, and water cannot be hydrolyzed by a single electrode.
Hz: Hertz. A measure of frequency in cycles per second.

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IAC: Idle Air Control.
IAT: Intake Air Temperature. AKA ACT
ICM: Ignition Control Module.
IDI: Indirect Injection.
Idle Air Control (IAC): A pulse-modulated solenoid valve which controls throttle bypass air to help control engine idle RPM. AKA Bypass Air Idle Speed Control solenoid (BPA-ISC).
IDM: Ignition Diagnostic Monitor.
IFS: 1. Independent Front Suspension; 2. Inertia Fuel Shutoff switch.
IGN GND: Ignition Ground.
Ignition: System used to provide high voltage spark for internal combustion engines.
Ignition Control Module (ICM): The module that controls the ignition system.
Ignition Diagnostic Monitor (IDM): A signal or circuit from the ignition control module to the EEC/PCM.
Incandescent Bulb: The earliest type of electric light; it operates by passing current through a resistive filament within an inert gas, generating enough heat to maket the filament glow. The inert environment prolongs the life of the filament (usually Tungsten), and certain gases (halogens) accentuate the light produced. They are relatively inefficient & fragile. Compare HID, Fluorescent, LED.
IMRC: Intake Manifold Runner Control.
IMS-EUL: Inferred Mileage Sensor/Extended Useful Life Module.
IMT: Intake Manifold Tuning.
Independent Front Suspension (IFS) or Independent Rear Suspension (IRS): A suspension system which allows either wheel to travel without inducing travel in the opposite wheel. Most incorporate a linkage which partially defeats this function called an anti-sway bar. They have the advantages of lower unsprung weight, better handling, & a smoother ride, but the disadvantages of more complex & delicate construction, more wearing parts, and more expensive alignment. Contrast Solid Axle.
Independent Shop: An auto repair business not associated with a vehicle manufacturer.
Indirect Injection (IDI): A diesel cylinder head design in which the fuel injector pintle is recessed in a pocket outside the combustion chamber.
Inertia: The physical tendency of a mass (an object) to maintain its current speed & direction (even if stopped) until acted on by an external force. Compare Momentum.
Inertia Fuel Shutoff (IFS): A safety system or device used on vehicles with an electric fuel pump that shuts off the fuel delivery system when activated by predetermined force limits. AKA inertia switch.
Inferred Mileage Sensor/Extended Useful Life Module (IMS-EUL): A small module attached to certain '87-91 instrument clusters which can be safely deleted. No documentation on its purpose or operation has been found. Sometimes referred to as "Infrared Mileage..." due to a typo in the Haynes manual.
Injection Pressure (IP): A sensor, signal, or circuit which indicates the pressure in the fuel rail.
Injector: A device for delivering metered pressurized fuel to the intake system or the cylinders. AKA fuel injector.
Intake Air: Air drawn through a cleaner, regulated by a throttle, and distributed to each cylinder by a manifold for use in combustion.
Intake Air Temperature (IAT): A sensor, signal, or circuit which indicates the temperature of the intake air. It may be in a runner in the intake manifold, in the air cleaner, or in the duct between them. AKA ACT.
Intake Manifold Runner Control (IMRC): A system, signal, or circuit which controls airflow through runners in the intake manifold.
Intake Manifold Tuning (IMT): Control of airflow through runners in a split intake manifold.
Integrated Electronic Ignition (EI): An Electronic Ignition system that has the Ignition Control Module (ICM) integrated into the PCM.
Integrated Vehicle Speed Control (IVSC): Cruise control system incorporated within the PCM, used primarily on diesels & vehicles with electronically-controlled throttle.
Intercooler: A component or system designed to cool the intake air, which has been heated by forced induction. The removal of heat from the pressurized air going into the intercooler increases the air density, which improves combustion efficiency, engine horsepower and torque. On some gasoline engines, the system consists of an additional radiator in the grille, a reservoir (independent from engine cooling system), an electric water pump, a heat exchanger (intercooler) located in the lower intake manifold and tubing to interconnect these components. On most diesel engines, heated & pressurized intake air from the turbocharger outlet is routed to a heat exchanger in the grille forward of the radiator, and then back to the intake manifold(s).
Intermittent: 1. A fault that may not be present or identifiable currently; 2. A wiper system or setting that pauses the motor to reduce smearing & noise.
IP: Injection Pressure.
IRS: Independent Rear Suspension.
ISO: International Standards Organization.
IVSC: Integrated Vehicle Speed Control.
IVV - Thermactor Idle Vacuum Valve (carburetor/vacuum)
JY: Junkyard
Kanooter Valve or Kanuter Valve or Kneuter Valve: A joke among mechanics & gearheads to detect amateurs. See KaleCo Automotive.
KAM: Keep Alive Memory.
KAPWR: Keep Alive Power.
Keep Alive Memory (KAM): A portion of the memory within the PCM that must maintain power even when the vehicle is not operating. Adaptive strategies & certain fault codes are stored here.
Keep Alive Power (KAPWR): Dedicated, unswitched power circuit that maintains KAM.
Key On Engine Off Self-Test (KOEO): A test of the EEC system conducted by the PCM with power applied and the engine at rest.
Key On Engine Running Self-Test (KOER): A test of the EEC system conducted by the PCM with the engine running and the vehicle at rest.
Knock: The sharp metallic sound produced when two pressure fronts collide in the combustion chamber of an engine. It may be caused by hotspots in the combustion chamber (either from poor engine design, carbon buildup, or overheating), high compression, low octane numbered fuel, a lean condition, ignition timing too far advanced (high BTDC), insufficient EGR flow, or incorrect spark plugs. It can cause severe engine damage, including burning through pistons, valve or head damage, overheating, catalyst damage, exhaust leaks, ruptured head gaskets, or backfire (and that resulting damage). AKA Valve Clatter, Dieseling, Preignition, Detonation, Pinging.
Knock Sensor (KS): A peizolectric sensor installed in the engine block which detects any vibration similar to engine knock.
KOEO: Key On Engine Off.
KOER: Key On Engine Running.
KPA: Kilopascal. Metric unit of pressure. 3.386 kPa = 1 inch of mercury (Hg.).
KPH: Kilometers Per Hour. Metric unit of speed. 1.6 KPH = 1 MPH; 0.6 MPH = 1 KPH.
KS: Knock Sensor.
L: Liters. Metric unit of volume.
Ladder Frame: The most common style of frame consisting of 2 parallel members (frame rails, roughly horizontal) connected by perpendicular members (crossmembers). Contrast Unibody, Monocoque.
LCD: Liquid Crystal Display.
LCV - EGR Load Control Valve (carburetor/vacuum)
LDDT: Light Duty Diesel Truck.
LDT: Light Duty (gasoline, CNG, or FF) Truck.
LDV: Light Duty (gasoline, CNG, or FF) Vehicle, generally passenger cars and light trucks under 6000 pounds GVWR.
LED: Light-Emitting Diode
LED Display: An electronic display consisting of an array of LEDs, used to generate characters, symbols, & patterns. Very large displays using several colors of LED can be used to create video displays, such as on blimps. Contrast LCD, VFD.
LEV: Low Emission Vehicle.
LFC: Low Fan Control.
LFP: Low Fuel Pump.
LHDE: Light Heavy Duty Engine.
LIFO: Last In First Out.
Light-Emitting Diode: An electronic device which uses semiconductor material to generate light. They are very efficient (very little heat compared to the light output) and have extremely long lifespans. Contrast Incandescent Bulb. See LCD Display.
LILO: Last In Last Out.
Limited-Slip Differential: A type of differential which uses constant friction in an attempt to keep both outputs turning at the same speed, while still allowing true differentiation when necessary. See "What's the DIFF?" Contrast Open Differential, Locker, Torque-Biasing Differential, Spool.
Lincoln-Locker: An OE open differential which has been welded solid, into a spool. It is named for the popular brand of welding machine. If done incorrectly, the axleshafts can never be removed, OR it can shatter during extreme use. See "What's the DIFF?"
Liquid Crystal Display (LCD): An electronic display which uses a thin layer of liquid crystal between layers of glass, and behind a polarizing filter. Transparent electrical terminals are embedded in the liquid layer so that, when a voltage is applied, the crystals polarize the light passing through them. The interaction between the crystals & the polarizing filter results in some areas of the display being black while others remain transparent. LCDs do not generate light, but can be placed in front of reflectors or lights to increase contrast. Common applications include pocket calculators, wristwatches, digital wall clocks, & certain computer monitors and TV screens. The effect is that characters or images can be generated in the shapes of the terminals in the display. Contrast LED, LED Display, VFD.
LNG: Liquified Natural Gas. See Natural Gas.
Locker or Locking Differential or Full-Locker: A mechanism which replaces the standard differential carrier and semi-permanently connects 2 output shafts (as in a differential) using springs & meshed teeth, but no gears. It does not provide true differentiation, but does allow the shafts to rotate at different speeds under certain conditions. See "What's the DIFF?" Contrast Selectable Locker, Mini-Locker, Open Differential, Limited-Slip Differential, Torque-Biasing Differential, Spool.
Locking Hub or Lockout: slang. See Hub Lock.
Long Block: An engine assembly consisting of a cylinder block, a crankshaft, all the bearings, all the connecting rods, all the pistons and rings, all the cylinder heads, a camshaft, timing gears/chains/covers, the assembled valvetrain, & most of the seals. Some also include an oil pump, an oil pan, a water pump, an intake manifold, a distributor, & a gasket set. Contrast Short Block, Smallblock, Bigblock.
Long Term Fuel Trim (LONGFT1 and 2): While the engine is operating in closed loop fuel, the short term fuel trim corrections can be "learned" by the PCM as long term fuel trim corrections. These corrections are stored in keep alive memory (KAM) in tables that are referenced by engine speed and load (and by bank for engines with two HO2S sensors forward of the catalyst). Learning the corrections in KAM improves both open loop and closed loop air/fuel ratio control. Advantages include: short term fuel trim does not have to generate new corrections each time the engine goes into closed loop; and, long term fuel trim corrections can be used both while in open loop and closed loop modes. Long term fuel trim is represented as a percentage, just like short term fuel trim, however it is not a single parameter. There is a separate long term fuel trim value that is used for each rpm/load point of engine operation. Long term fuel trim corrections may change depending on the operating conditions of the engine (rpm and load), ambient air temperature and fuel quality (% alcohol, oxygenates, etc.). When viewing the LONGFT1/2 PID(s), the values may change a great deal as the engine is operated at different rpm and load points. The LONGFT1/2 PID(s) will display the long term fuel trim correction that is currently being used at that rpm/load point.
Long-Tube Header: A header whose collector is below the oil pan or outside the frame rails. See Header. Compare Shorty.
Low Fan Control (LFC): Controlling the low speed cooling fan.
Low Fuel Pump (LFP): An output circuit or signal from the PCM which controls the low speed fuel pump.
LPG: Liquified Petroleum Gas. See Natural Gas.
M: fuel code for Methanol
M5OD: A designation for 3 distinct manual transmissions: the Mazda M5OD-R1 used in mid-sized trucks; the Mazda M5OD-R2 used in fullsize light trucks; and 2 variants of the ZF S5-42 & -45 (both called M5OD-HD) used in fullsize heavy-duty light trucks. All have an Aluminum case with integral bellhousing, and were available in 2- or 4WD configurations.
M85: Fuel containing 85% methanol alcohol. Fuel methanol (M85) is a mixture of approximately 85% commercial grade methanol (M100) and 15% unleaded gasoline. The resulting fuel has a higher octane rating than unleaded regular gasoline, allowing engine designs with higher compression and corresponding greater engine efficiency and performance (power). Winter blends may contain up to 30% unleaded gasoline to enhance cold engine starts, hence the sometimes-used M85-M70 designation. Severely cold weather may require additional measures for reliable starting. Methanol corrodes some metals and may cause some plastic and rubber components to swell, break down or become brittle and crack, especially when mixed with gasoline. Special materials and procedures have been developed for vehicles and the dispensers used by M85 fuel providers. Since methanol has less energy per gallon, fuel economy in miles per gallon will decrease as the percentage of methanol goes up. However, the FFV uses more of the energy available in the fuel when running on M85-M70 than on gasoline. Flexible fuel vehicles burning fuel methanol have lower exhaust emissions than comparable gasoline vehicles.
M/T: Manual Transmission/Transaxle.
MAF: Mass Air Flow.
MAF RTN: Mass Air Flow Return.
Malfunction Indicator Lamp (MIL): A required on-board indicator to alert the driver of an emission related malfunction. May read either "CHECK ENGINE" or "SERVICE ENGINE SOON." Compare CEL, SES.
MAN VAC - Manifold Vacuum (carburetor/vacuum). Measurement can yield valuable diagnostic information about the engine.
Manifold: A device designed to collect or distribute a fluid, like air, exhaust, coolant, or fuel.
Manifold Absolute Pressure (MAP): A sensor which detects the absolute pressure of the intake manifold air.
Manual Lever Position Switch (MLPS or MLP): A sensor, signal, or circuit which indicates the selected drive modes of the transmission. AKA NSS, PNP, TR, DTR.
MAP: Manifold Absolute Pressure.
Mass Air Flow (MAF): A system or sensor which provides information on the mass flow rate of the intake air to the EEC/PCM for engine management.
Mass Air Flow Return (MAF RTN): A return circuit for the MAF sensor.
MD: Misfire Detection.
Mechanical Secondary Air Injection: A pump driven system for providing secondary air using a belt driven pump. Contrast Pulse Air Injection System & Electronic Secondary Air Injection.
Methanol: Wood alcohol; CH3OH. An inexpensive but poisonous fuel additive used to reduce the cost of fuel, and emissions. Blends containing more than ~5% methanol require special engine management & fuel system materials. See M85.
MFI: Multiport Fuel Injection.
MFS: Multi-Function Switch.
MHDDE: Medium Heavy Duty Diesel Engine.
MHDE: Medium Heavy Duty (gasoline, CNG, or FF) Engine.
Microprocessor: A digital processor on a chip which performs logical operations on data.
MIL: Malfunction Indicator Lamp.
Mini-Locker: An aftermarket part which replaces the contents of an open differential carrier with a spring & tooth mechanism to semi-permanently lock the outputs together. See "What's the DIFF?" Contrast Locker (Full-Locker).
Mini-Spool: An aftermarket part which replaces the contents of an open differential carrier in order to lock the outputs together. See "What's the DIFF?" Contrast Spool (Full-Spool).
Minivan: A midsize passenger van under 5000lbs GVWR, generally unibody FWD.
Misfire: Any event in the cylinder that causes a sudden change in the speed of the crankshaft.
Misfire Detection (MD): Circuitry designed to detect a misfire by monitoring changes in acceleration of a wheel mounted on the crankshaft through a CKP.
MLPS or MLP: Manual Lever Position Switch. See DTR.
Module: A self-contained group of electrical/electronic components, which is designed as a single replaceable unit.
Momentum: the quantity of energy carried by a moving mass, relative to some fixed point. High speed &/or mass results in high momentum.
Monitor Box: An optional EEC system test device which connects in series with the PCM and its harness and permits measurements of PCM inputs and outputs.
Monocoque: A lightweight style of vehicle frame used mostly in race cars & motorcycles consisting of a central structure, roughly tubular, similar to a crane boom. Modern Corvettes use this. Contrast Unibody, Ladder Frame.
Motor: 1. A device which converts electrical energy into rotating mechanical energy; 2. A device which converts vacuum into linear motion (vacuum motor); 3. An engine (slang)
Mount: A mechanical connection that holds a major component to a vehicle's chassis, such as an engine mount (motor mount), transmission mount, or body mount. Most isolate the component's vibrations from the chassis with rubber &/or a viscous fluid (fluid mount), usually silicone grease or oil. Solid mounts are used in high-load appliacations where occupant comfort is less of a concern than absolute reliability, such as engine mounts for flat-track racers.
Muffler: A resonating chamber used to reduce sound emissions in an airflow, usually engine exhaust.
Muffler Bearing: A joke among mechanics & gearheads to detect amateurs. See KaleCo Automotive.
Multiport Fuel Injection (MFI): A fuel-delivery system in which each cylinder is individually fueled.
Multi-Function Switch (MFS): A switch that combines the functions of turn signal, hazard, beam select, flash-to-pass, wiper & interval, and sometimes cornering lamp control.
Multiplexing : The process of communicating several messages over the same signal path. The increased number of modules on the vehicle dictates a more efficient method of communication. This process allows multiple modules to communicate with each other through the signal path (BUS+/BUS-). Modules communicate with the powertrain control module using Standard Corporate Protocol (SCP) which determines the priority in which the signals are sent. (See SCP.) Multiplexing reduces the weight of the vehicle by reducing electrical wiring.
MY: Model Year.
NAAO: North American Automotive Operations.
Natural Gas (NG): A system capable of using compressed or liquefied natural gas or LPG fuel for vehicle operation.
Naturally Aspirated (N/A): An unforced-induction system which allows air to flow into the intake manifold by atmospheric pressure alone. Contrast Turbocharger, Ram Air, Supercharger.
NC: Normally Closed.
NCP: Non Compliance Penalty.
Nerf Bar: A medium-weight beam below the rocker panel designed to fend-off minor damage when a vehicle drives off-road, and also as a step. Contrast Step Bar; Rock Slider; Exo-Cage.
Neutral Start/Safety Switch (NSS): A sensor, signal, or circuit which indicates the selected non-drive modes of the transmission. AKA MLP, MLPS, PNP, TR, DTR.
NG: Natural Gas.
NO: Normally Open.
NOx: Oxides of Nitrogen.
NP 208: A common early chain-driven 4WD (no internal differential) part-time 2-speed transfer case built by New Process Gear with a fixed front yoke output on the L side. The NP 208F variant was built for Ford trucks. It was replaced by the BW 1342 & 1356 beginning around 1986. Eventually all Ford fullsize 4WD light trucks got the 1356, including the F550 PSTD.
NP 435: A common 4-speed manual transmission built by New Process Gear, known for its robustness & durability, even when used in 5-ton trucks. Although no longer in production, it is still in use in many UPS delivery trucks, and is a popular swap for off-road vehicles.
NSS: Neutral Start/Safety Switch.
NTSB: National Traffic Safety Board. A federal office which oversees many aspects of motor vehicles.
NVH: Noise, Vibration, Harshness. A classification of vehicle concerns.
O: fuel code for Other; chemical symbol for Oxygen.
O2S: Oxygen Sensor.
OASIS: On-line Automotive Service Information System.
OBD: On Board Diagnostic.
OC: Oxidation Catalytic Convertor.
OCIL: Overdrive Cancel Indicator Lamp. AKA TCIL
OCS: Overdrive Cancel Switch. AKA TCS
OCT ADJ: Octane Adjust.
Octane Adjust (OCT ADJ): A circuit or shorting connector (jumper) that alters engine strategy to compensate for changes in fuel octane.
OE: Original Equipment. Parts installed on a vehicle at the factory. Contrast Direct-Replacement, Aftermarket.
OEM: Original Equipment Manufacturer. The original producer of factory-installed parts.
OHC: Overhead Cam.
OMV or DMV: Office/Department of Motor Vehicles. A state office which typically oversees & administers motor vehicle registration, titles, & driver's licenses.
On Board Diagnostic (OBD): A system that monitors some or all computer input and control signals. Signal(s) outside of the predetermined limits imply a fault in the system or in a related system.
Open Circuit: A circuit which does not provide a complete path for current flow (Off, broken circuit). Contrast Closed Circuit.
Open Differential: A differential which divides the input torque (engine) inversely to the amount of resistance on the outputs (traction). See "What's the DIFF?" Contrast Limited-Slip Differential, Locker, Torque-Biasing Differential, Spool.
ORVR: On-board Refueling Vapor Recovery.
OSS: Output Shaft Speed.
Output Shaft Speed (OSS): A sensor, signal, or circuit which indicates the rotational speed of the transmission output shaft.
Overhead Cam (OHC): An engine configuration that uses a single camshaft positioned above the valves.
Overlay Card: A plastic card used with the monitor box to identify EEC signals for each engine. The card also programs the monitor box for auto mode measurements.
Oxidation Catalytic Convertor (OC): A catalytic convertor system that reduces levels of HC and CO.
Oxygen Sensor (O2S): A sensor which detects oxygen (O2) content in the exhaust gases. Compare HEGO, HO2S.
Ozone: A toxic blue gaseous form of oxygen (O3) formed naturally by electric discharge or high-altitude exposure to ultraviolet radiation. It blocks UV & other radiation from striking the surface of the Earth, but is broken down by many industrial chemicals including older refrigerants.
PA: Public Address; a loudspeaker system, on vehicles typically connected to a CB radio.
PAnt: Power Antenna
Parameter Identification (PID): Identifies an address in the PCM memory which contains vehicle operating information.
Park/Neutral Position (PNP): A sensor, signal, or circuit which indicates the selected non-drive modes of the transmission. AKA MLP, MLPS, NSS, TR, DTR.
Particulate: Small solid matter found in exhaust gases, especially prevalent in diesel engines.
PATS: Passive Anti-Theft System. A factory anti-theft system which disables the fuel injector drivers if the code chip in the ignition key does not match the stored code.
PC: Passenger Car.
PCM: Powertrain Control Module.
PCV: Positive Crankcase Ventilation.
PCV Valve: A replaceable gravity- & flow-controlled 1-way metering valve in the PCV system. Because it is exposed to crankcase sludge, it will fail if not replaced regularly. Its failure can result in engine fires, diluted or contaminated engine oil, accelerated wear throughout the engine, poor economy, DTCs, increased emissions, and NVH.
PF: Purge Flow.
PFE: Pressure Feedback EGR.
Photochemical: The action of light on air pollutants which contributes to smog.
PI: Performance-Improved; a ~1997 revision to the head design of the 4.6L modular engine standardized ~2001; often confused with Police Interceptor (slang) (a badge on certain Crown Victorias with P71 options).
PID: Parameter Identification.
Pigtail: An electrical connector with preinstalled terminals, each of which has a short wire attached. It is generally used to replace a damaged original connector, but may be used to add new systems.
Pinging: See Knock.
PIP: Profile Ignition Pickup.
Pitman Arm: A steering mechanism which converts the rotating motion of the steering shaft into the swinging of an arm. Contrast Rack & Pinion.
PL: Power Door Locks
PM: Power Mirrors
PNP: Park/Neutral Position switch. See DTR.
PO: Previous Owner
Polarity: A characteristic of a binary physical phenomenon, such as electricity (which can be polarized + or -) or a magnetic field (which can be polarized N or S).
Polarity-Reversing Circuit: An electronic circuit used to drive a motor, which is capable of driving it either direction by means of reversing the polarity supplied to the motor. Examples include Ford power windows, power locks, power antennae, power seats, power mirrors, power adjustable pedals, & sunroofs. GM typically uses double-wound motors, which are heavier, bulkier, & less efficient, but require simpler switches & circuits to control.
Polarized Light: Visible light which has passed through a polarizing filter, as is commonly found on LCD displays & polarized sunglasses. Once polarized, the light cannot pass through a 2nd filter unless the 2nd is aligned with the 1st. Any change in the alignment results in the light being further dimmed. If the 2nd is 90° offset from the 1st, virtually no light passes. Light is also polarized by LCD (which is how the LCD generates the black areas) or by reflection off glass or water (which is why driving & fishing sunglasses are sometimes polarized to eliminate the glare).
Portal Axle: An axle assembly whose outboard ends incorporate an offset drive mechanism, placing the majority of the axle's bulk ABOVE the centerline between the roadwheels. This creates a "portal" between the wheels, allowing greater ground clearance. Some agricultural vehicles use portal axles (often with hydraulic drives); the UniMog truck uses solid portal axles; the HMMWV & Hummer (H1) use independent front & rear portal suspensions; MatTracks (TM) create a portal configuration.
Positive Crankcase Ventilation (PCV): A system which forcibly draws crankcase emissions back through the engine where they are burned. The PCV valve regulates the amount of ventilating air and blow-by gas to the intake manifold, and prevents backfire from traveling into the crankcase. The PCV valve should be mounted in a vertical position. Sometimes incorporated with the evaporative emissions system.
Potentiometer: An adjustable resistance component commonly used as a position sensor for rotatable shafts (Example: TP Sensor).
Power Ground (PWR GND): The main ground circuit in the EEC system. Distinguished from signal ground (SIG RET) & case ground.
Power Steering: A system which provides additional force to the steering mechanism, reducing the driver's steering effort. It most often incorporates a hydraulic pump powered by the FEAD supplying pressure to a gear box or rack.
Power Steering Pressure (PSP): A sensor, switch, signal, or circuit which indicates the pressure in the power steering system.
Power Take Off (PTO): 1. A mechanical connection for using engine power for aftermarket equipment such as hydraulic pumps, generators, & agricultural implements. 2. An EEC input signal used to disable On Board Diagnostic Monitors during PTO(1) use.
Powertrain: The elements of a vehicle by which motive power is generated and transmitted to the driven wheels.
Powertrain Control Module (PCM): The module that controls the EEC system. Compare EEC, ECC, ECM, ECU, MCU, OBD.
PPM: Parts Per Million. A measure used in emissions analysis.
Preignition: See Knock.
Pressure Feedback EGR (PFE): An EGR system that monitors EGR pressure to control EGR flow.
PRNDL or 'prindle': shift indicator (slang).
Profile Ignition Pickup (PIP): A sensor, signal, or circuit which provides crankshaft or camshaft position data for ignition synchronization.
Programmable Speedometer/Odometer Module (PSOM): A module that processes vehicle speed information for use in various electronic systems, displays speed on an analog face, and displays odometer data in a digital LCD. The PSOM can be programmed to accommodate various tire and axle combinations. It is unaffected by gear ratio changes.
PROM: Programmable Read-Only Memory. ROM without program instructions.
Protocol: A set of rules for the exchange of information on a network.
PSOM: Programmable Speedometer/Odometer Module.
PS: 1) Power Seats; 2) Power Steering; 3) Power Sunroof
PSP: Power Steering Pressure.
PSTD: PowerStroke Turbo Diesel.
PTO: Power Take Off.
Pulse Width (PW): The length of time an actuator, such as a fuel injector, remains energized, measured in milliseconds or degrees. Compare Duty Cycle.
Pulse Width Modulation (PWM): A signal pattern characterized by flat peaks of varying duration but constant height separated by an absence of signal (ground) which controls the intensity of an output by varying the signal duty cycle.
Purge Flow (PF): Amount of fuel vapor burned in the engine.
PVC: PolyVinyl Chloride; a common type of plastic. Often confused with PCV.
PW: 1) Power Windows; 2) Pulse Width.
PWM: Pulse Width Modulation.
PWR GND: Power Ground.Pump: A device used to raise, transfer, or compress fluids by suction, pressure or both.
Quarter (Panel): The body panel behind the doors.
Quick Test: A functional diagnostic test of the EEC system consisting of vehicle preparation and hookup, KOEO, KOER and Continuous Memory Self-Tests.
R: combustion code for Otto Cycle Rotary (Wankel) engines.
RABS: Rear Antilock Brake System.
Rack & Pinion: A steering mechanism which converts the rotating motion of the steering shaft into the linear motion of a gear rack. Contrast Pitman Arm.
Ram: A linear hydraulic actuator.
RAM: Random Access Memory. Memory into which information can be written as well as read. It is typically volatile (does not survive power loss) and much faster than (nonvolatile) EEPROM.
Ram Air: A forced-induction system which uses the vehicle's forward motion to provide pressurized air to the intake manifold. Contrast Turbocharger, Supercharger, Naturally Aspirated.
Recall: A program authorized by the manufacturer whereby a known fault or issue with a motor vehicle is repaired, usually without additional cost to the owner, & usually without expiration. A recall generally applies to a very specific group of vehicles, and the manufacturer identifies each VIN to the OMV of each state, which then furnishes the manfuacturer with the registered owner's name & mailing address. Recalls are generally overseen by NTSB &/or DOT, but are administered by the manufacturer. AKA FSA. Contrast TSB.
REDOX: Reduction/Oxidation Catalytic Convertor.
Reduction/Oxidation Catalytic Convertor (REDOX): A catalytic convertor system that is designed to operate at high temperatures. At low temperatures, it reduces levels of HC and CO. At high temperatures, it reduces levels of HC, CO, and NOx.
Reference Voltage (VREF): A dedicated circuit that provides a 5.0 volt signal used as a reference by certain sensors.
Regenerative Brakes: A system for slowing a moving vehicle which stores the energy, instead of simply converting it to heat as normal brakes do. Regenerative braking systems may use dynamos to store the energy electrically, air compressors or hydraulic pumps to store it as pressure, or other means. They are most commonly used on commercial & industrial vehicles which make frequent stops, like city buses.
Relay: A generally electromechanical device in which connections in one circuit are opened or closed by changes in another circuit. Almost all Ford vehicles use a starter relay, and most are mounted to the right inner fender or wheelwell near the battery. Often confused with Solenoid.
Relay Module (RM): A module containing two or more relays.
REM: Rear Electronic Module.
Repetitive Spark: Multiple firings of individual spark plugs at engine speeds below 1000 RPM to improve idle quality and improve emissions. AKA Multiple Spark Discharge (MSD) (TM).
RF: Radio Frequency. A band of electromagnet frequencies between ultrasonic & microwave.
RFI: Radio Frequency Interference. A high-frequency form of EMI.
Return (RTN): A dedicated sensor ground circuit.
RM: Relay Module.
Roadster: An open passenger car with 2 doors, with or without a removeable/collapsible roof. Compare Convertible.
Rock Slider: A heavy beam below the rocker panel designed to carry the weight of the body over rocks when a vehicle drives off-road. Contrast Step Bar; Nerf Bar; Exo-Cage.
Rocker Arm: A lever in the head operated by the camshaft (possibly through lifters & pushrods) which opens the valve.
Rocker Panel: The body panel below the doors.
RON: Research Octane Number. The laboratory-measured octane number of an automotive fuel. Contrast actual octane number, nominal octane number.
Routine: A group of related tasks, such as a series of diagnostic tests.
Root-Mean Square (RMS): A mathematical operation to produce a useable value for signals whose average value is 0. Necessary for all AC signals, and generally calculated based on 60Hz. DMMs which specify "RMS" on their packaging calculate it based on the actual measured frequency, and are therefore far more accurate for automotive signals, whose frequencies often vary.
RPM: Engine Revolutions Per Minute.
RTN: Return.
RWD: Rear Wheel Drive. A powertrain system which delivers engine power to a differential in the rear axle only. Contrast FWD, AWD, 4WD.
S: Spark port (carburetor/vacuum) A nipple on a carburetor whose vacuum response is designed to control the vacuum advance of a distributor.
S: combustion code for Otto 4-Stroke-Cycle Piston engines.
SAE: Society of Automotive Engineers.
Safety Certification Label: A sticker showing the manufacturer, build date, VIN, & other information needed to show compliance with vehicle safety laws & standards. It is most often applied in the driver's door jamb area, and usually contains a bar code version of the VIN. Some also indicate installed options & cargo capacities. AKA VIN Sticker, Door Jamb Sticker.
SC: Supercharger or supercharged.
Scan Tool (ST): A device that interfaces with and communicates information on a data link.
SCP: Standard Corporate Protocol.
Secondary Air: Air provided to the exhaust system anywhere downstream of the exhaust valves.
Secondary Air Injection (AIR): A pump-driven system for providing secondary air.
Secondary Air Injection Bypass (AIRB): See TAB.
Secondary Air Injection Diverter (AIRD): See TAD.
Sedan: A passenger car with 4 doors.
Selectable Locker or Selectable-Locking Differential: An aftermarket differential with a mechanism that can convert it to behave as a spool when the operator chooses. See "What's the DIFF?" Contrast Open Differential, Limited-Slip Differential, Locker, Mini-Locker, Torque-Biasing Differential, Spool, Mini-Spool.
Self-Test: A general term for three distinct aspects of the EEC system Quick Test: Key On Engine Off, Key On Engine Running, and Continuous Memory. Compare OBD.
SEMA: Secondary Equipment Manufacturers' Association. A trade guild of businesses who supply non-OE parts, OR a trade show they host each year.
Semi-Floating Axle: An axle assembly whose axleshafts bear the weight of the vehicle at only 1 end. Contrast Full-Floating Axle.
Sensor: The generic name for a device that senses either the absolute value or a change in a physical quantity such as temperature, pressure or flow rate, and converts that change into an electrical quantity signal. A sensor is typically an analog device. Its digital counterpart is a switch.
Sensor Ring: See Tone Ring.
Sequential Multiport Fuel Injection (SFI): A multiport fuel delivery system in which each injector is individually energized and timed relative to its cylinder intake event. Normally fuel is delivered to each cylinder once per two crankshaft revolutions in four cycle engines and once per crankshaft revolution in two cycle engines.
Servo: A remote actuator which can be regulated to a precise position, as opposed to simply an extreme of its range of motion. Common examples include cruise control servos, HVAC door servos, & power seat or power mirror motors WITH memory. Those without memory capability are simply motor-driven mechanisms, but do not qualify as servos.
SES: Service Engine Soon light. See MIL.
SFI: Sequential Multiport Fuel Injection.
Shield: A conducting sleeve that surrounds wires to be electronically isolated from electromagnetic interference (EMI).
Shift Indicator Lamp (SIL): A lamp that indicates the preferred shift points for manual transmission/transaxle vehicles.
Shift Solenoid (SS): A device that controls shifting in an automatic transmission.
SHO: Super High Output.
Short Block: An engine assembly consisting of a cylinder block, a crankshaft, all the bearings, all the connecting rods, all the pistons and rings, & few if any seals. Some also include a camshaft, timing gears/chains/covers an oil pump, an oil pan, & a gasket set. A short block does NOT include cylinder heads, valve covers, or intake manifold. Contrast Long Block, Smallblock, Bigblock.
Short Circuit: A connection between a circuit and any other point. While generally used to indicate an undesirable connection, all wires are short circuits between the terminals they connect. The expression "short" indicates that there is very little resistance between the 2 points. Contrast Open Circuit, high resistance, Off.
Short Term Fuel Trim (SHRTFT1 and 2): If the oxygen sensors are warmed up and the PCM determines that the engine can operate near stoichiometric air/fuel ratio (14.7 to 1 for gasoline), the PCM goes into closed loop fuel control mode. Since an oxygen sensor can only indicate rich or lean, the fuel control strategy must constantly adjust the desired air/fuel ratio rich and lean to get the oxygen sensor to "switch" around the stoichiometric point. If the time between switches are the same, then the system is actually operating at stoichiometry. The desired air/fuel control parameter is called short term fuel trim where stoichiometry is represented by 0%. Richer (more fuel) is represented by a positive number and leaner (less fuel) is represented by a negative number. Normal operating range for short term fuel trim is +/- 25%. Some calibrations will have time between switches and short term fuel trim excursions that are not equal. These unequal excursions are used to run the system slightly lean or rich of stoichiometry. This practice is referred to as using "bias". For example, the fuel system can be biased slightly rich during closed loop fuel to help reduce NOx. Values for SHRTFT1 and 2 may change a great deal on a scan tool when the engine is operated at different rpm and load points. This is because SHRTFT1 and 2 will react to fuel delivery variability that can change as a function of engine rpm and load. Short term fuel trim values are not retained after the engine is turned off.
Shorty or Shortie or Short-Tube Header: A header whose collector is above the oil pan and inside the frame rails. See Header. Compare Long-Tube Header.
SI: Sequential Injection; System International d'Unites (the modern international version of the metric system).
Signal: A fluctuating electric quantity, such as voltage or current, whose variations represent information.
SIG RTN: Signal Return.
Signal Return (SIG RTN): A dedicated sensor ground circuit that is common to two or more sensors.
SIL: Shift Indicator Lamp.
Slider: 1) A sliding window; 2) A rock slider.
Slip Yoke: A telescoping connection between a splined shaft (usually the output shaft of a transmission or transfer case) and a U-joint in a driveshaft. Most fullsize Ford pickups use a slip yoke, except those with the BW 1342.
Slotted Rotor: A disk brake rotor which has had spiral slots machined into its surface. Historically, this was done to improve braking performance due to poor friction materials which contained adhesives & other contaminants that produce gas when heated (causing the pads to "float" away from the rotor like a hovercraft), and which also produce varnish on the friction surfaces. The slots not only allow this gas to escape, but also clean the pads. Modern pads do not suffer from these problems, so modern slots are purely cosmetic. However, removing metal from the disk's surface causes the pads & rotors to wear faster, and causes heat to build up to higher temperatures; both of which reduce braking effectiveness. See Cross-drilled Rotor, Wilwood FAQ.
Smallblock: An engine family of varying displacements that share some parts & characteristics, most of which have lower displacement than most of those in another family of engines from the same manufacturer. Contrast Short Block, Long Block, Bigblock.
SME: Society of Manufacturing Engineers.
Solenoid: A device consisting of an electrical coil which, when energized, produces a magnetic field in a plunger which is pulled to a central position. A solenoid may be used as an actuator in a valve or switch. A solenoid-operated switch is called relay. Few Fords before 1990 used a starter with a solenoid, but even after that, a starter relay was often still used. Most other brands of '75-95 US vehicles use only a starter solenoid with no relay, which results in most parts suppliers calling Ford-type relays 'solenoids'.
Solid Axle: A suspension unit (typically a driving axle) which rigidly connects the 2 wheels, most often by a tube containing a differential and axleshafts. Front (steering) solid axles also include steering knuckles & universal joints of some type. Contrast IFS/IRS.
Spanner: A style of wrench that grips the face of the fastener (usually a large, thin nut), as opposed to the sides. Common applications include antenna nuts & wheel bearing adjusting nuts on 4WD vehicles.
Spark Output (SPOUT): A shorting plug, connector, signal, or circuit which transmits the desired spark timing information from the PCM to the ICM.
Speed: The magnitude of velocity (regardless of direction).
Spool or Full Spool: A single solid piece of metal which connects an axle's ring gear to the axleshafts, providing no differentiation. See "What's the DIFF?" Contrast Differential, Locker. Compare Lincoln-Locker.
SPOUT: Spark Output.
SS: Shift Solenoid.
ST: Scan Tool.
Standard Corporate Protocol: A communication language used by most automotive manufacturers for exchanging bi-directional messages (signals) between stand-alone modules and devices. Two or more signals (multiplexed) can be sent over one circuit. Included in these messages is diagnostic data that is output over the BUS+ and BUS - lines to the data link connector (DLC). This information is accessible with a scan tool.
Standing Wave Ratio: A measure of the efficiency of a radio transmitter (usually a CB) & its antenna system. The ideal value is 1, meaning all of the energy leaving the radio's output is radiated from the antenna. Deviations from this can be caused by poor connections, coiled antenna cables, or improperly tuned antennae (wrong effective length for the average frequency). It is not related to Ground Plane.
Step Bar: A light beam below the rocker panel designed to carry the weight of a few people as they enter/exit the vehicle. Contrast Rock Slider; Nerf Bar; Exo-Cage.
SuperCharger or SuperCharged (SC): A forced-induction system, or its primary component: a rotating mechanism driven mechanically by engine power to provide pressurized air to the intake manifold. Contrast Turbocharger, Ram Air, Naturally Aspirated.
SULEV: Super Ultra Low Emission Vehicle.
SUT: Sport-Utility Truck. A class of vehicles that generally includes 4-door wagon-body open-bed light trucks, & minivans designed to look like 4-door open-bed light trucks.
SUV: Sport-Utility Vehicle. A class of vehicles that generally includes wagon-body light trucks, & minvans with slightly increased ground clearance and short wheelbase. Some are available with 4WD or AWD.
SV CBV - Solenoid Valve Carborator Bowl Vent (carburetor/vacuum)
Switch: A device for making, breaking, or changing the connections in an electrical circuit.
SWR: Standing Wave Ratio.
System: A group of interacting mechanical or electrical components serving a common purpose.
T: combustion code for Turbine
TA: Traction Assist. A software addition to anti-lock braking which reduces wheel slippage.
TAB: Thermactor Air Bypass
TACH: Tachometer.
Tachometer (TACH): A circuit that provides input for an electronic tachometer display.
TAD: Thermactor Air Diverter
TB: Throttle Body.
TBI: Throttle Body Injection. AKA CPI
TC: Traction Control. Combines anti-lock braking and axle torque reduction (through electronic throttle control) to control wheel slippage.
TCC: Torque Convertor Clutch.
TCIL: Transmission Control Indicator Lamp.
TCS: Transmission Control Switch.
TDC: Top Dead Center; the point at which a given crankshaft lobe (usually #1) is perfectly aligned with its connecting rod, and the piston is at its maximum distance from the crankshaft.
Tear Tag: The two—piece adhesive label attached to the PCM to identify its calibration.
Terminal: A point of attachment for any electrical conductor, generally within a connector. Some terminals are left unconnected for testing, or for optional circuits which are not installed.
Test: A procedure whereby the performance of a product is measured under various conditions.
Thermactor Air Bypass (TAB): A signal, circuit, solenoid valve, vacuum line, or air valve which directs the output of the secondary air pump either to the TAD or to an exhaust muffler.
Thermactor Air Diverter (TAD): A signal, circuit, solenoid valve, vacuum line, or air valve which directs the flow of secondary air either to the exhaust manifolds (upstream) or to the catalytic converter (downstream), through a check valve in either case.
Thermistor: A temperature dependent resistor, like that used in CHT and ECT sensors.
Three Way + Oxidation Catalytic Convertor (TWC+OC): A catalytic convertor system that has both Three Way Catalyst (TWC) and Oxidation Catalyst (OC). Usually secondary air is introduced between the two catalysts.
Three Way Catalytic Convertor (TWC): A catalytic convertor system that reduces levels of HC, CO, and NOx.
Throttle: A valve for regulating the supply of a fluid, usually air or an air/fuel mix, to an engine.
Throttle Body (TB): The device containing the throttle.
Throttle Body Injection (TBI): A fuel-delivery system in which fuel is delivered to the throttle body to be distributed through the intake manifold to the cylinders.
Throttle Position (TP): A sensor, signal, or circuit which indicates the position of the throttle plate.
Tier 0: California regulations effective prior to 1993 model year, and Federal regulations prior to 1994 model year.
Tier 1: California and Federal regulations effective beginning in 1993 model year and Federal regulations beginning in 1994 model year.
Timing: Relationship between spark plug firing and piston position usually expressed in crankshaft degrees before (BTDC) or after (ATDC) top dead center of the compression stroke.
TK - Throttle Kicker (carburetor/vacuum)
Tone Ring: A toothed or notched iron or steel disk, which is attached to a rotating part. AKA Exciter Ring, Sensor Ring
Torque: The force of rotation.
Torque-Biasing Differential: A differential whose internal mechanisms vary the division of the input torque (engine) proportionally to the outputs' resitance (traction). See "What's the DIFF?" Contrast Open Differential, Limited-Slip Differential, Locker.
Torque Convertor: A device which by its design multiplies the torque in a fluid coupling between an engine and transmission/transaxle.
Torque Convertor Clutch (TCC): A solenoid valve, signal, or circuit which controls the application and release of the torque convertor clutch.
TFT: Transmission Fluid Temperature.
TLEV: Transitional Low Emission Vehicle.
TP: Throttle Position.
TR: Digital Transmission Range sensor.
Traction Control (TC): Combines anti-lock braking and axle torque reduction to control wheel slippage.
Transaxle: A device consisting of a transmission and axle drive gears (differential) assembled in the same case. Compare "Transmission."
Transducer: A device that receives energy from one medium and transfers it to another. For example, thermal energy is converted to an electrical signal through a thermocouple; light energy is converted to electricity through a solar cell.
Transmission: A device which selectively increases or decreases the ratio of relative rotation between its input and output shafts. Compare "Transaxle." Current Ford transmission naming convention is as follows:
* The first character, a number, is the number of forward gears.
* The second character, either the letter "F" or "R," represents front (transaxle) or rear (transmission) wheel drive.
* The next characters, a grouping of numbers, represents 1/10 the design torque capacity of the transmission/transaxle.
* The last character, if used, is one of the following:
* * "E" for electronic shift
* * "N" for non—synchronous shift
* * "S" for synchronous shift
* * "W" for wide ratio
Transmission Control Indicator Lamp (TCIL): Indicates that the TCS has been activated. Typically mounted to the end of the shift lever of an automatic transmission, and incorporated with the TCS. AKA OCIL
Transmission Control Switch (TCS): Modifies the operation of electronically controlled transmissions. Typically mounted to the end of the shift lever of an automatic transmission, and incorporated with the TCIL. AKA OCS
Transmission Fluid Temperature (TFT): A sensor, signal, or circuit which indicates the temperature of transmission fluid.
Transmission Range (TR): A sensor, signal, or circuit which indicates the range in which the transmission is operating.
Turbine Shaft Speed (TSS): A sensor, signal, or circuit which indicates the rotational speed of the transmission turbine shaft.
Turbocharger: A forced-induction system, or its primary component: a rotating mechanism driven by exhaust gas flow to provide pressurized air to the intake manifold. Contrast Supercharger, Ram Air, Naturally Aspirated.
TSB: Technical Service Bulletin. A document published by a motor vehicle manufacturer containing technical information intended to be used by trained technicians to assist in identifying & repairing a specific concern on a specific group of vehicles. It generally contains criteria for identifying affected vehicles, specific procedures for the repair, a list of required &/or recommended parts, and the authorized labor time for which a flat-rate dealership technician will be paid.
TSS: Turbine Shaft Speed.
TTB: Twin Traction Beam.
TVS - Throttle Valve Solenoid (aka SolePot, Dashpot) (carburetor/vacuum)
TVV - Thermal Vacuum Valve (carburetor/vacuum)
TWC: Three Way Catalytic Convertor.
TWC+OC: Three Way + Oxidation Catalytic Convertor.
Twin Traction Beam (TTB): A copyrighted name for the Dana 28IFS, 35IFS, 44IFS, & 50IFS axles used exclusively in Ford 4WD/AWD light trucks from the early 80s to the late 90s. Its design is the basis for many long-travel IFS axles used on off-road race trucks.
Two Valve (2V): Two valves, one intake and one exhaust, per cylinder.
ULEV: Ultra Low Emission Vehicle.
Vacuum: Air pressure below ambient. Gasoline engines operate with a vacuum in the intake manifold to control power output. Diesels cannot operate with manifold vacuum.
Vacuum Booster: A power-assist mechanism for vehicle brakes which uses vacuum pressure to amplify the force applied to the brake master cylinder. Contrast HydroBoost.
Vacuum-Fluorescent Display (VFD): An electronic display which uses fluorescent gases inside a glass vacuum chamber to produce luminescent characters & symbols. VFDs are relatively heavy, complex, fragile, & inefficient compared to other display types, but have the advantages of high contrast & producing their own light. They are typically bright green, and are commonly used on radios & all-digital instrument clusters. Contrast LED Display, LCD.
Vacuum Reservoir: A chamber (usually molded plastic or a steel can) to provide vacuum for actuators during conditions when engine-generated vacuum may not be available.
Vacuum Tree: A vacuum manifold with several nipples radiating from a central fitting.
Valve: A device by which the flow of liquid, gas, vacuum, or loose material in bulk may be started, stopped or regulated by a movable part that opens, shuts or partially obstructs one or more ports or passageways. A "Valve" is also the moveable part of such a device.
Valve Clatter: See Knock.
Van: A fullsize or larger truck whose cab significantly overhangs its engine bay, resulting in the front wheelwells encroaching into the front passengers' footwells. Most vans are built on ladder frames.
Vapor Management Valve (VMV): A valve that controls the amount of fuel vapor burned in the engine.
Variable Load Control Module (VLCM): A module that provides variable control of various EEC components.
Variable Reluctance: A process of passing a varying magnetic field through wire windings and inducing a voltage.
VCT: Variable Camshaft Timing. A system which adjusts the mechanical timing between the crankshaft & the camshaft(s). AKA VVT
VCV - Vacuum Control Valve (carburetor/vacuum)
VDF: Visctronic Drive Fan. An electrically-assisted viscous fan coupling.
VDV - Vacuum Delay Valve; Vacuum Diverter Valve (carburetor/vacuum)
VECI Label: Vehicle Emission Control Information Label. A sticker showing vehicle-specific information, codes, & diagrams describing the factory-installed emissions systems, and tune-up information.
Vehicle Power (VPWR): A switched circuit that provides power to the EEC system. Compare "Battery Positive Voltage (B+)."
Vehicle Speed Control (VSC): Cruise control system. Early types use a vacuum servo & speed sensor on the speedometer cable. Later types use an electronic servo & speed sensor in the transmission or differential.
Vehicle Speed/Engine RPM Limiter: A strategy to prevent damage to the powertrain. The powertrain control module (PCM) will disable some or all of the fuel injectors whenever an engine rpm or vehicle overspeed condition is detected. The vehicle will exhibit a rough running engine condition, and the PCM will store a Continuous Memory DTC P1270. Once the driver reduces the excessive speed, the engine will return to the normal operating mode. No repair is required. However, the technician should clear the PCM and inform the customer of the reason for the DTC. Excessive wheel slippage may be caused by sand, gravel, rain, mud, snow, ice, etc. or excessive and sudden increase in rpm while in NEUTRAL or while driving.
Vehicle Speed Sensor or Signal (VSS): A sensor, signal, or circuit which provides vehicle speed information. Until ~1989, this was used exclusively by the VSC, and from '89~92 it was also used for E4OD control on F-series trucks. It is typically installed in the speedometer cable, the transmission tailhousing, or the transfer case rear output housing. Contrast ABS(2).
VFD: Vacuum-Fluorescent Display.
VIN: Vehicle Identification Number. A 17-digit code uniquely identifying a vehicle standardized in 1981. The encoded information typically includes country of origin, manufacturer, GVWR/brake capacity/restraint type, body style, body size, chassis type, engine size, MY, production plant, & serial number. There is also a verification code to prevent random VINs from being generated.
VIN Sticker: See Safety Certification Label.
Viscosity: A measure of the ability of a fluid (usually a liquid) to flow. AKA Weight in oils.
VLCM: Variable Load Control Module.
VMV: Vapor Management Valve.
VOM: Volt-Ohm Meter. Non-specific, so generally used for analog (needle) meters to differentiate from DVOMs & DMMs (DIGITAL meters).
VPWR: Vehicle Power.
VRDV - Distributor Vacuum Retard Delay Valve (carburetor/vacuum)
VREF: Reference Voltage, generally ~5VDC supplied from the PCM to certain sensors.
VSC: Vehicle Speed Control.
VSS: Vehicle Speed Sensor (early); Vehicle Speed Signal (late).
WAC: Wide Open Throttle A/C Cut-off.
Wagon Body: A vehicle whose cargo area is integral to its cabin structure, most commonly: 4-door station wagons, SUVs, vans, & minivans. Box vans are not included, but panel vans are.
Warm Up Oxidation Catalytic Convertor (WU-OC): A catalytic convertor system designed to lower HC and CO emissions during engine warm up. Usually located in or near the exhaust manifold.
Warm Up Three-Way Catalytic Convertor (WU-TWC): A catalytic convertor system designed to lower HC, CO, and NOx emissions during engine warm up. Usually located in or near the exhaust manifold.
Wastegate Control: A device that opens a turbocharger's wastegate in case of overboost.
Wide Open Throttle (WOT): A condition of maximum airflow through the throttle body.
Wide Open Throttle A/C Cut-off (WAC): Turns A/C system off during wide open throttle or certain other operating conditions.
WOT: Wide Open Throttle.
WU-OC: Warm Up Oxidation Catalytic Convertor.
WU-TWC: Warm Up Three-Way Catalytic Convertor.
Yoke: A 1-piece connection between a splined shaft & a U-joint in a driveshaft. One end is a splined sleeve that fits over the shaft & inside an oil seal. The other end spreads across the caps of the U-joint and attaches either by 2 U-bolts & 4 nuts, 4 bolts & 2 straps (GM & Dodge), or a cast mating cap with 4 bolts (double-cardan applications).
Z: fuel code for Electric
ZEV: Zero Emission Vehicle.
Zip Tube: Another name for "fresh air duct" or "air inlet duct".


An acronym is an abbreviation that can be pronounced as a word, like:

Nazi (National Sozialistische Deutsche Arbeiters Partei)
SCUBA (Self-Contained Underwater Breathing Apparatus)
LASER (Light Amplification by Stimulated Emission of Radiation)
SONAR (Sound Navigation & Ranging)
MASH (Mobile Army Surgical Hospital)
WASP (White Anglo-Saxon Protestant)
GIGO (Garbage-In; Garbage-Out)
WYSIWYG (What You See Is What You Get)

HMMWV (High-Mobility Multipurpose Wheeled Vehicle - hummvee) & STFU (Shut The F**k Up - stoofoo) are commonly used as acronyms, even though they aren't really.

TTT (To The Top), BTT (Back To Top), FTW (For The Win), NWS (Not Work-Safe), NSFW (Not Safe For Work), TTB (Twin Traction Beam), TFI (Throttle-body Fuel Injection), & IBTL (In Before The Lock) are just abbreviations because they can't be pronounced as words.

Searchability: dictionary, define, definition, word, mean, meaning, list

[Elway]

Thanks for the help with the jargon. Now I don't have to go and google all of these abbreviations when searching for help on the forums!

[broncodude26]

Thanks Steve.

[miesk5]

me too, a thanks Steve! ....... wherever you are.............

[JuggernautXLT'88]

Suggestion:

Sticky, lock, and delete replies?

Excellent material IMO.

[A1Fiddler]

I remember this being posted before. X2 on the sticky.

[Dustin]

Originally Posted by JuggernautXLT'88

Suggestion:

Sticky, lock, and delete replies?

Excellent material IMO.

steve gets pissed when you do that to his threads....