Woke up this morning and its cold ass shit out, got in my 92 ls started her up and the temp gauge spike up all the way to red (like my eyes) 
. Got scared at first do popped the hood and saw no leakage, radiator hose cold, I topped off the reservoir just in case . Then went back turn on the car ( not start it) and saw the temp gauge spike all the way up. So even with the car turned off and the engine cold i am still getting and overheating reading. So made a conclusion that it might be the ECT (engine coolant temp sending unit). But i would like to know if any body else ran into this problem, also would like to know what you guys think.
ECT Sending unit is where I’d start. Faulty ECT switch or ECT sensor will not affect your gauge, so they shouldn’t be the culprit.
The ECT switch is located right under the distributor right, and the sensor located by the thermostat housing? BTw there is no connector on the ect sending unit how do i connect the new one on.
you need to find the oem connector from another harness or you can use aftermarket connectors, but those don’t fit tight some times.
ECT switch is on the back of the block or the thermostat housing depending on the year of the motor. The ECT sensor is the two pin sensor on the side of the head. The ECT sending unit is the single pin sending unit on the side of the head (looks kinda like a headphone jack).
did anyone figure this one out I have the same problem i was looking for the short to grown on my yellow green wire and i didn’t find it yet