Temp. Gauge doesn't work...need to fix ASAP!

The temperature gauge on the dash does not work at all...How can I determine when my car is overheating if it does not read. How can I possibly fix the problem in order to take on a long trip?

Car information:

00' Pontiac Grand Prix GT
mileage: 121328

Hey I don't think my fans doesn't come on at all...how can I check?

Hey I don't think my fans doesn't come on at all...how can I check?

This post has been moved from Tips & Maintenance to the regular Grand Prix forum and then merged with your other thread/post which is the same topic or related.

Check the electrical connection to the engine coolant temperature sensor (ECT) and the 5 volt reference signal at the input. If that is good maybe the ECT sensor is bad which provides the signal to the temp gauge and PCM module so it knows when to turn on the cooling fans.

Also, if it is above 45 degrees F which I am assuming since you are in Miami the cooling fans should come on with the A/C on. Otherwise the fans are programmed to turn on at 220 degrees in low speed and around 230 degrees in high speed.

Thats for the reply...but I need to know where and what is the 5 volt reference signal at the input?


This post has been moved from Tips & Maintenance to the regular Grand Prix forum and then merged with your other thread/post which is the same topic or related.

Check the electrical connection to the engine coolant temperature sensor (ECT) and the 5 volt reference signal at the input. If that is good maybe the ECT sensor is bad which provides the signal to the temp gauge and PCM module so it knows when to turn on the cooling fans.

Also, if it is above 45 degrees F which I am assuming since you are in Miami the cooling fans should come on with the A/C on. Otherwise the fans are programmed to turn on at 220 degrees in low speed and around 230 degrees in high speed.

The ECT is located below the thermostat on the lower intake manifold. Just undo the electrical connector and measure the PCM 5 volt low reference signal at the input pin. See pic below.

http://i5.photobucket.com/albums/y186/lizzywiz/ect3.gif

Thanks for the reply...but I was wondering if you have an actual photo so I can pinpoint what you're talking about. I believe I know what you mean. So are you indicating all I have to do is disconnect the wiring and reconnect it back into the temp. coolant sensor and/or replace the temp. coolant sensor?

The ECT is located below the thermostat on the lower intake manifold. Just undo the electrical connector and measure the PCM 5 volt low reference signal at the input pin. See pic below.

http://i5.photobucket.com/albums/y186/lizzywiz/ect3.gif

I need an actual photo of the 5Volt Reference signal and the exact location of the ECT sensor....Is it possible I can have the procedure for replacing the following ECT sensor and Redo or reconnect the 5volt reference signal?