Temperature gauge?

Tiny
JBEAURAIN
  • MEMBER
  • 2004 CHEVROLET SUBURBAN
  • 5.0L
  • V8
  • AUTOMATIC
  • 80,000 MILES
The temperature gauge has spun all the way around and points down. It will some times come back to around 160 degrees when I try starting it and keep clicking the ignition key. I changed the temperature sending unit, but that didn't help. Is the gauge itself bad and if so how hard is it to change
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Friday, September 5th, 2014 AT 1:34 PM

3 Replies

Tiny
CARADIODOC
  • EXPERT
More than likely it's a simple mechanical issue. If they're using the same type of gauges everyone else went to, it is a "stepper" motor with a pointer on it. A computer places the armature in a specific setting through four electromagnet coils. If something happens to make the gauge jump for an instant, and it goes over half-way around, the next time you start a cold engine that armature will go back to "cold", but it takes the shortest route, which can be clockwise. With speedometers and tachometers you simply drive or rev the engine more than half scale, then the pointer will find its way there, then follow the speed back down.

With a temperature gauge, if you have two separate temperature sensors yet, one for the Engine Computer and a different one for the gauge, the one with a single wire is for the gauge. You might be able to unplug it and ground that wire while the ignition switch is on. When you unground it, the gauge should go back down the right way.

You can remove the crystal and physically push the needle back to its proper position. Most scanners have a gauge test menu that commands the gauges to go to various positions. Doing that will bring all of them back down. Some vehicles have a test sequence that is initiated by pressing certain switches in the right order.
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Friday, September 5th, 2014 AT 8:32 PM
Tiny
BOB JONES
  • MEMBER
  • 2004 CHEVROLET SUBURBAN
  • V8
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
The temp guage is normal at straight up 210* but now goes to 3/4 high, halfway between 210 and 260* Approxamately 235*. When driving down the street it climbs to 235 but at a stop light temp goes down to normal 210* When I put the heat on full to see what effect this has the heat blows cold with no effect on the temp. Is this the thermostat gone bad and if so where in the system is it located. Sometimes simple service on this car gets complicated.

Read your reply. One question was not answered. Where, exactly, in the system is the thermostat located. I do not want unnessarily unhook anything looking for it. Please locate it. Thanks
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Wednesday, May 26th, 2021 AT 11:42 AM (Merged)
Tiny
RACEFAN966
  • EXPERT
I would have it checked to see if the temp is really getting that high. Many shops use an infered temp gun to check temps. So call around and ask if one of the shops would be willing to check it for you to see if it is really getting that hot. If it is then I would check for coolant lose. If it isn't getting that hot then change the temp switch for the guage. Let me know what you find and we will go from there.
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Wednesday, May 26th, 2021 AT 11:42 AM (Merged)

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