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my temp gauge jumps crazy all over the place. *solved* melted wire insulation


cutlass1991

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In the 97 CS 3100, the temp gauge has been acting weird. Most of the time it reads below the normal operating temp, even after running the car all day. The needle never seems to move. Then out of nowhere, the needle will jump up into the red and bounce all over the place. This happens most often when I rev the engine; at idle it usually doesn't jump around. I have replaced the temperature sensor on the engine block facing the front of the car, I used a 19mm socket to change and I think it had 3 wires. Replacing had absolutely no effect on the problem.

 

The cooling system was flushed and filled about 3-4 months before this problem started. I did not replace the t-stat. My heater works great. I'm just worried that the fans aren't turning on and I can't tell if I'm overheating.

 

where should I go from here?

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Theres two sensors for the temp. If you did the one on the front of the engine, you did the wrong one. That one is just for the PCM. The one for the cluster is on the rear head, drivers side. Its a one wire sensor.

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Jay's on the right track IMHO. If you already replaced the front one, go for the rear driver side. I can't remember if it has only one wire like Jay says it does though. Chances are he's correct.

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NO! a 97 should have ONE 3 wire sensor.

 

look and see. the 94 and 95 3100 would have had two just by comparision.

 

I had a jumping gauge issue on my 92 lumina, when the wire came in contact with the egr pipe and melted and intermittently grounded.

 

does it even move at all, except when it is jumping? I bet the wire is broken off and intermittantly grounding when you rev the engine.

 

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Well, I went to autozone, advance, and the dealership..all of them seemed to have trouble finding the right part. I ended up getting this:

0423071125no8.jpg

 

0423071125abm1.jpg

 

This looks similar to the one i did on the front of the engine, except that this only has two wire contacts on it instead of 3. No one had a temp sensor with just 1 contact in the receptical.

 

I searched around the rear valve cover and couldn't find anything that looked like this sensor. I did find this plug hanging loose though:

 

0423071033ch6.jpg

 

 

 

I think part of my problem is I'm not sure what this thing looks like.

 

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NO! a 97 should have ONE 3 wire sensor.

 

look and see. the 94 and 95 3100 would have had two just by comparision.

 

I had a jumping gauge issue on my 92 lumina, when the wire came in contact with the egr pipe and melted and intermittently grounded.

 

does it even move at all, except when it is jumping? I bet the wire is broken off and intermittantly grounding when you rev the engine.

 

 

 

bingo! I traced the wire from the sensor back to where it plugs in. I found the plug resting on the valve cover, got it repositioned and found some melted wires that were shorting. Thanks!

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the red plug is for the variable power assist, an option that your car does not have.

 

it was standard on later 3.4 cars, and may have been optional on ours.

 

 

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