So when I got my 98 the temp gauge wasn't working. Come the find out the plug going to the sending unit was gone no where to be found, my guess is that it was cut off. So I just bought an aftermarket gauge and connected it to the sending unit and works fine. I just need to know how to tie it in to the PCM so it doesn't think the motor isn't up to temp and keep feeding it more gas than needed. Which wire on the PCM should I tie in to? Gas is getting expensive and I don't need to be using more than I need to.

Also, if anyone can tell me where to original plug, that plugs to the sending unit, is in the harness or provide me with a photo of theirs so I can attempt to find the wire or somethin. It would be much appreciated. Thanks.

 

The engine coolant temp sensor, (ECT) is near the thermostat housing. The PCM sends data from the sensor to the BCM. The BCM sends the data to the instrument cluster logic module. The logic module sends data to the temperature gauge in the cluster. If the ECT sensor is disconnected, it will set a DTC, (Diagnostic Trouble Code) and turn on the SES light. Don't try to modify the sensor or the wiring to the PCM.

 

So does the pcm know that it is up to temp even thought the sending unit is only hooked to the aftermarket gauge?

 

If the SES light is not illuminated, I would say that you don't have the aftermarket sender connected to that circuit. There are 2 wires at the sender: Black goes to ground and yellow is the signal wire to the PCM.

 

The ses light is not on. And it isn't an aftermarket sender. It's the oem one on the side of the motor. I just have an aftermarket gauge. Would you happen to know where the plug that goes to the sender on the side of the motor?

 

In post #2, disregard the first sentence, it's incorrect, sorry. On your '98, the temp sensor is in the left cylinder head. The sensor wires break out of the main engine harness just behind the injector housing. There is a black plastic split loom, ~3/8" in diameter, with one black and one yellow wire in it, and a black electrical connector at the end. The split loom runs over the left rocker arm cover and down to the temp sensor in the left cylinder head, between cylinders 3 & 5.