Thread: PCM vs temp gauge mystery

Hey guys I'm new here and have a issue I canT solve myself I own a 2000 grand prix gt 3.8 non supercharged and I recently have done the LIM gaskets and the upper as well and new o rings on the injectors I also replaced the coolant temp sensor and the thermostat and I have done and oil change and flushed the coolant and bled the system several times but I keep having an issue with overheating When I'm driving the temp Gauge stay at the half way point but when I'm not moving and just idling the car get very hot almost into the red. And the fans don't turn I have checked all the relays and fuses the fans will turn on about 10 min after turning the ac on but thats about it but the thing is I hooked a good scanner to my car and the PCM says my temp is normal it stays steady at 90 degrees celsius while the temp gauge at the same time says I'm almost in the red so about 120 Celsius so I would like some advice as to what might be my problem with the gauge all the wires look good and it used to work fine before I did the LIM

There are two sensors built into our one temp sensor. That's why it's a three wire. One feed coming in then pcm and gauge heading out.

I'd replace the sensor too.

use periods and commas. it makes things a lot easier to read because i can actually breathe between sentences.

you sure there isnt a massively cold thermostat in there? or none at all?

Yeah..it changes stuff. You didn't give us the full story. The story led us to believe that it worked fine before you dicked with it. Therefore we had to figure you were the cause.

Now I gotta go back and rewrite my whole book on the problem. To make your story telling the problem and the previous owner the evil guy of the story. Geez, there's gonna be a lot of white out on these pages.

Look up some of the codes for temp sensor etc at gearchatter.com and get the resistor values and temps expected. stuff them into the connector as it suggests and you can test the gauge etc.

coolant temp sensor (ECT).

it doesnt.

Originally Posted by RyanL

i have the same problem but never checked with a scanner. what is the etc sensor? im a damn mechanic and dont know the abbreviation lol but quick fix is usually just the sensor?

Between your two posts in this thread.. uh you got me wondering. What are you a mechanic of? Doesn't seem like you are working on the average car.