Did a search and found some similar problems but no solutions.

Working on the girlfriend's '87 IROC. When you turn the key-on the gauge flickers and centers itself on cold; but when you crank the engine or go to bulb test the gauge pegs hot and gets stuck in the bezel. I checked the wiring diagram for the system and it apparently gets a signal straight to ground in these two key positions. A straight ground signal on the sender wire also results in this condition. What is going on here? As far as I can tell everything is working as its supposed to unless there is supposed to be a physical stop in the gauge that is no longer there??

 

yeah its supposed to peg when you put key in start..i would take the trim plate, lens and bezel off and make sure the retainer screws that hold the gauge in are snug, and if they are try gently pushing the needle towards the gauge face.

 

I understand its supposed to peg, but what is supposed to stop it from getting pinned? I'll probably just put in some wire as a stop, but i'd like to know whats changed that it gets stuck now and not before.

 

The needle could be getting stuck on the metal trim...had that problem once..

What IROC Monkey said: take off the trim and reseat the temp gauge..When putting everything back dont tighten the nuts to tight or the metal trim could rub on the Temp needle and will get pegged again

 

Alright, took a known good gauge from another car and checked it out. Apparently there is some kind of internal resistance that went away in the gauge, I plan to take it apart and see how it works exactly. With no resistance, when it gets the straight ground through the ignition switch for the test sweep it flys out of control into the bezel and pegs. When I get the gauge apart i'll see if there is a way to fix it, or if its just worn out for good.

 

Well Thank You Chris for toying with that damn gauge....it ended out that the gauge itself was at fault.....I too have been doing research onto this issue, and apparently the gauge (whatever drives the needle to read) can actually wear out, thus causing the needle to pin itself between gauge itself and the trim bezel. Upon inspection the know gauge that works is visually different compared to the gauge in question(the exhisting one out of my car). In handling the gauges my gauge needle flopps around like a fish out of water, the operating gauge needle shows tension and needle does not move around upon free will. MANY MANY people automatically think they have a bad ground/sensor/sender or an electrical issue not worth chasing...but after some time spent testing the coolant system...chances may be the gauge itself is bad. I currently have my car in its storage unit...and forgot the bad gauge that hopefully Chris and I will be dis-assemble to find out what makes it "tick"...or in this case fail. I thank you again Chris for messing with the whole damn set up to rule out everything else...and figure out it was the gauge...the LAST thing I wanted to do was give up and wire in a ugly looking aftermarket temp gauge drilled into my dash and have a dead gauge in my cluster. ...ooohhh that would drive me INSANE!!!

 

Oh yeah they do go bad occasionally. Usually when I have seen them fail they dont move at all. The nice thing about the 82-89 Camaro cluster is its plug and play exept for the speedo. So malfunctioning units are easy to replace. Although if you're gonna repair it, it would be nice to know the procedure and the results.

As far as appearance, there are some variations through the years, mostly 82-84, pretty much everything 85-89 is the same.

 

I tried getting my gauge apart when it went bad. They're most definitely non-serviceable.

The Fiero guys have the same problem with their temperature gage. Except they can run a resistor in line, so instead of pegging the gage (which over time breaks the gage) it'll only hit 280 or so. Looking at the schematics, the only place you could throw a resistor in our setup is on the PCB, which would be a monumental pain in the rear.