Spinning temperature gauge

Tiny
TRUBLUROOKIE
  • MEMBER
  • 1993 CHEVROLET SILVERADO
  • 5.7L
  • V8
  • 4WD
  • 263,000 MILES
I have a K1500 model. Every time I start the truck the temperature gauge needle will fly around. It will bury the needle on the hot side and my check engine light will come on. After starting the truck the gauge will spin wildly. Is this a gauge problem or a coolant temperature sensor problem?
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Wednesday, April 19th, 2017 AT 8:25 PM

9 Replies

Tiny
STEVE W.
  • EXPERT
Could be either one, or more likely the wire from the sender is shorted to ground.
First test, Unplug the sending unit and see what the needle does when you turn on the key. If it still goes high you have a gauge or wiring issue. If it does not then change the sender.

If the needle still spikes, check the senders wiring for an area where it is shorted to ground as that is the most likely problem.
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Wednesday, April 19th, 2017 AT 9:27 PM
Tiny
TRUBLUROOKIE
  • MEMBER
There is also a wire coming off of the sender that goes between the stud and nut on the right side of the thermostat housing. I have been told that is a ground wire but I have also been told there should not be a ground for the sender unit. Should that be there or was it added at a later time for some other reason?
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Thursday, April 20th, 2017 AT 4:06 PM
Tiny
STEVE W.
  • EXPERT
Should be a black wire that goes to a ground inside the ECM and a yellow wire that is the signal wire to the ECM. Sounds like someone added a different ground. The issue there is that the engine may be at a different ground potential than the ECM and it could make the gauge read wrong.

That ground normally runs into the harness and connects with the black ground wire for the TPS sensor. They are in the upper right of the attached wiring diagram.
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Thursday, April 20th, 2017 AT 6:12 PM
Tiny
TRUBLUROOKIE
  • MEMBER
I know this is an old thread but I replaced the temperature sensor connector wire and blue clip and I still have the same issue. One thing I noticed was when the truck is cold and I climb into the driver's side I can make the needle bounce and go crazy if I lightly bounce and tilt the truck towards the driver's side. Does this give you any better clue?
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Saturday, December 23rd, 2017 AT 12:48 AM
Tiny
STEVE W.
  • EXPERT
Check the grounds for the dash. They are under it to the left behind the area where the E-brake is. Almost has to be a loose connection or a shorted wire. When you get in do you pull on the steering wheel?
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Saturday, December 23rd, 2017 AT 1:37 AM
Tiny
TRUBLUROOKIE
  • MEMBER
No, I just stand on the step bar and hold on to the door
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Saturday, December 23rd, 2017 AT 1:49 AM
Tiny
STEVE W.
  • EXPERT
OK then it shouldn't be near the column.
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Saturday, December 23rd, 2017 AT 6:18 AM
Tiny
TRUBLUROOKIE
  • MEMBER
I can't find the ground wires. Do you have a picture or a description of what they should look like?
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Sunday, January 14th, 2018 AT 2:32 PM
Tiny
STEVE W.
  • EXPERT
If you look behind the drivers side kick panel they should be there. There will be a few wires going to a ring terminal that will be screwed to the metal about 2" up from the floor.
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Sunday, January 14th, 2018 AT 8:51 PM

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