is trying to tell you is that you replaced your Engine Coolant Temperature Sensor
(ECT), which sends a signal to your PCM to assist in determining proper Air/Fuel Ratio.
I would not have replaced this Sensor
unless I received a 21, 51, 61, 116, 117 or 118 trouble code, which would indicate a failure in the PCM coolant temperature circuit. When you receive one of these codes, the next step is to go to the ECT Sensor
and test for a resistance value of 58,750-40,500 Ohms cold and 3600-1840 Ohms hot, and replace the Sensor
if it is out of range. Then test the harness connector for an approximate 5.0v signal voltage, and look for a short or ground if required.
What he is recommending is that you replace your Coolant Temperature Sender
which sends a signal to your dash gauge. These are cheap and frequently go bad giving you an erroneous temperature gauge reading.
Test it by grounding the single wire that goes to the Sender
and momentarily key-on your truck. If the gauge goes full tilt, replace your Sender
. If all is well and the problem continues, then look elsewhere.
To be clear, the Engine Coolant Temperature Sensor
has nothing to do with regulating engine temperature nor signaling the gauge. It only sends information to the PCM.
See Temperature Gauge Sending Unit
Photo from Gacknar's SuperMotors web-site.