97 Granx Prix "Red" Temp Light Coming ON

[duke_winchester]

I have a 1997 Pontiac Grand Prix GTP with 169,000 miles on it. I noticed today that the "Check Gauges" indicator came up in my heads up display and also on my dash panel the Red Temp Light came on below the engine temperature gauge, just to the right of where it says "Apply brake to shift out of park". What is this light? The car is not running hot or overheating. Thanks

[richtazz]

If the gauge is reading correctly and the car is not overheating, it may ust be an issue with the instrument cluster.

[duke_winchester]

What does this red "temp" light indicate though? It is not the normal orange temp light that comes on.

[brcidd]

Are you sure it's not the low coolant light? Check your owner's manual to be sure.

[duke_winchester]

Its not the low coolant light, as that is in the upper left of the gauge cluster, is orange, and says "low coolant". This light is red, says "temp", and is on the lower right next to the thing that says "apply brake to shift from park"

[brcidd]

Well, typically it means you are overheating- is it real? You will have to tell us, Next time it happens, pull over, open hood.. are cooling fans on? Is coolant low? is coolant gurgling into reservoir? does engine seem too hot? There is a chance your ECT is bad- a scan tool will help determine this.

[duke_winchester]

The car is not overheating, as the light comes on when the car is first started from a completely cool condition. There is an SES light on. I have not had it scanned yet. The temp gauge appears to be acting strangely as well, as when i first start the car, the needle on it shoots up above the red and then comes back down.

[brcidd]

Well, then chances are real good the pending code is going to point to the temp sensor...easily replaceable.

[BNaylor]

Since you are getting a check gauges warning on the HUD probably more like a IP Cluster issue as Rich mentioned. However, you can double check the ECT - Engine Coolant Temperature sensor. Run a calibration check with a multimeter. It will be a resistance check based on temperature.

Also see what DTC is stored with an odb-ii scan tool to see if it is even related.

[duke_winchester]

So I scanned the code and it came back "low voltage from ECT sensor", so I replaced the sensor. The SES light and the temp light went off, but now the temp gauge is reading way hot in and staying in that range, even though the thermostat is opening and the cooling fans are coming on. What the heck is going on here? Please help

[duke_winchester]

Also, the check gauges light in the HUD is gone, but the cooling fans are not coming on until the temp gauge reads about 230 degrees

[BNaylor]

Originally Posted by duke_winchester

but the cooling fans are not coming on until the temp gauge reads about 230 degrees

Thats normal if the A/C is off. So was that with A/C on or off? When you replaced the ECT sensor did you use any plumber's/teflon tape? It should not be used since the casing of the ECT needs to be properly grounded.

Do you feel as the engine is actually overheating? Based on the high engine temps its a possibility.

[duke_winchester]

I was wrong about my thermostat opening properly. I removed it and ran the car without it and the temp seems to be running within the normal range right now. I will have to test it out some more tomorrow, but given the radiator is fairly new, and so is the waterpump, the hoses look good, fans are working: the thermostat seems a likely candidate.

[duke_winchester]

I am still unsure as to whether it is the thermostat. I drove the car for a while today (without the thermostat in place), and the temp still slowly climbed to above normal. At idle, it was pinned on 210 degrees. I did not use teflon tape on the sensor. Any other ideas?

[brcidd]

Is radiator hot up and down and side to side when idling at 210 degf?