Temp gauge stays on 100F

[Nathanc03]

Hello, I have a 1988 Old Cutlass Supreme and am having time with the temp gauge. The gauge stays on 100F and never moves while driving the car, I checked the sensor and it showed no resistance at all. Replaced it with an autozone sensor which also showed no resistance then replaced it with an AC Delco that now shows resistance which increases as the engine warms up, still no change at the gauge. I then removed the cluster and cleaned the nuts and copper contacts on the plastic circuit board, still not change on the gauge. Pulled the cluster again and applied 12v to the common and gauge terminal which caused the gauge to go below 100F. I would have expected it to max out. Then reinstalled the cluster and as soon as I turned the ignition it went back to 100F. I am at a loss on what to check next, I have had mice issues in the past, but would think if it was a wiring issue it wouldn’t have went back to 100F when I turned the ignition back on. Any help appreciated.

Thanks,
Nathan

 

[Supa.Slo.SS]

Hello, I have a 1988 Old Cutlass Supreme and am having time with the temp gauge. The gauge stays on 100F and never moves while driving the car, I checked the sensor and it showed no resistance at all. Replaced it with an autozone sensor which also showed no resistance then replaced it with an AC Delco that now shows resistance which increases as the engine warms up, still no change at the gauge. I then removed the cluster and cleaned the nuts and copper contacts on the plastic circuit board, still not change on the gauge. Pulled the cluster again and applied 12v to the common and gauge terminal which caused the gauge to go below 100F. I would have expected it to max out. Then reinstalled the cluster and as soon as I turned the ignition it went back to 100F. I am at a loss on what to check next, I have had mice issues in the past, but would think if it was a wiring issue it wouldn’t have went back to 100F when I turned the ignition back on. Any help appreciated.

Thanks,
Nathan

Maybe its the gauge itself? Did it use to read higher than 100F? I don't how often they fail but maybe that's the issue? I'd buy a cheap aftermarket one and compare the temps just to rule it out. Maybe the mice do a part of a ground wire? I have been told, if you don't have good grounds it causes some funky things to happen.

 

[G_RIDE_81]

Adding to the convo:
Also thought I had a bad sensor. I just got a new sensor, tested the wire by grounding and the gauge swept hot and back down when disconnected. However, the gauge went off the chart to a 3 o'clock position. Should it have gone that far? Or do I need another gauge?

Thanks in advance.