PTAaron Posted March 15, 2014 Report Share Posted March 15, 2014 (edited) ('94 Cutlass Supreme3.1L engine) I'm dealing with bigger issues at the moment determining if my head gasket is blown or not, but this is something I'd prefer to fix while I have things apart: Last weekend car overheated. After cooling down the temp gauge still reads maxed out when the key is turned to the run position. It drops back down to the "cold" needle position when power is off. Does not matter if car is running or not - as soon as power goes to the instrument cluster the needle spikes. I replaced the coolant sensor near the thermostat last night - thinking that was the problem, but that wasn't it. What is my next thing to investigate? Edited April 1, 2014 by PTAaron Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted March 15, 2014 Report Share Posted March 15, 2014 you have a 1-wire temp sender that is in the head(i want to say the front head), has a unique connector that just slips on and off. if it were to fall off, it should read absolute minimum on the guage. if the wire for it were connected to ground somewhere, that will force it to read maximum. so, if you don't have harness issues, you have a sender issue. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted March 15, 2014 Report Share Posted March 15, 2014 hmm..... alldata is showing it on the rear head. Quote Link to comment Share on other sites More sharing options...
PTAaron Posted March 15, 2014 Author Report Share Posted March 15, 2014 I'll check the wire... unless they sold me a defective sender that shouldn't be it. Hrm. Guess I'll try it with the harness disconnected and see what it does. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted March 15, 2014 Report Share Posted March 15, 2014 which sensor did you replace? one that looks like that is what drives the dash guage. single, permanantly attached wire, always green. that is the one the PCM uses for its purposes. two-wire, connector plugs directly into it, rather than a pigtail like the single-wire. Quote Link to comment Share on other sites More sharing options...
PTAaron Posted March 15, 2014 Author Report Share Posted March 15, 2014 which sensor did you replace? one that looks like that is what drives the dash guage. single, permanantly attached wire, always green. that is the one the PCM uses for its purposes. two-wire, connector plugs directly into it, rather than a pigtail like the single-wire. Option 2. Damn. We just ran across option one on the manifold and said "hey I bet that goes to the temp gauge." Quote Link to comment Share on other sites More sharing options...
PTAaron Posted March 15, 2014 Author Report Share Posted March 15, 2014 Under what name will I find the correct sensor? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted March 15, 2014 Report Share Posted March 15, 2014 the 1-wire is typically referred to as a sender, with the 2-wire being a sensor. Quote Link to comment Share on other sites More sharing options...
PTAaron Posted March 16, 2014 Author Report Share Posted March 16, 2014 Thanks! Part will be in tomorrow afternoon. Quote Link to comment Share on other sites More sharing options...
PTAaron Posted March 16, 2014 Author Report Share Posted March 16, 2014 FYI: If you throw the sender unit at the ground with enough force it breaks into 3 pieces. We had a hell of a time getting the sensor out - so accidentally flew across the garage once it finally came out. Quote Link to comment Share on other sites More sharing options...
dhdolphns Posted March 24, 2014 Report Share Posted March 24, 2014 theres a TSB on 92-95 cutlass and other 3.1 cars that is for Temp gauge not reading correct temp of engine..its a wiring harness kit to go from the 2 wire coolant temp sensor and the 1 wire (green wire) temp sensor to the 3 wire coolant temp sensor.. you can check out the info I found by link below. http://www.justanswer.com/chevy/37jd6-95-olds-cutlass-supreme-sl-temp-gauge-gauge-goes-temp-sensor-tsb.html Quote Link to comment Share on other sites More sharing options...
PTAaron Posted March 24, 2014 Author Report Share Posted March 24, 2014 Thanks for the info. Replacing the single wire sensor/sender fixed the problem. Turns out I had mistakenly believed that the 2 wire sensor was also the gauge sender. I've got a lot to learn with these cars. Quote Link to comment Share on other sites More sharing options...
Night Fury Posted March 24, 2014 Report Share Posted March 24, 2014 We all do. They are mysterious beasts. No one here knows everything. Quote Link to comment Share on other sites More sharing options...
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