Temp Gauge triggers the "ENGINE" idiot light - Engine not overheating at all

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Richard Clasby, Dec 7, 2017 at 1:45 AM.

  1. Richard Clasby

    Richard Clasby Registered User

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    Even when the engine is off for days, the Temp Gauge never goes down to "L" it always initially reads high then, after starting, it moves past "H" and triggers the "Engine" light. But the engine is not running hot and not overheating. It seems as though the gauge just starts out too high (way to the right and almost past the H) then when the engine heats up it moves slightly more to the right and triggers the "ENGINE" idiot light. Any thoughts on fixes? Is it just a poorly calibrated gauge? I was thinking of pulling the gauge cluster and just pushing the Temp Gauge Indicator back to the left. Is it a physical trigger? It seems it...
     
  2. whiteboyslo

    whiteboyslo FNG

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    Not linked. There are two sensors, one that runs the gauge and another that triggers the light.

    Mike
     
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  3. Macrobb

    Macrobb Full Access Member

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    However, if the temp /switch/(which triggers the light) turns on, it'll max out the gauge too.
    If it's off, the gauge works off an actual sender.
     
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  4. Thewespaul

    Thewespaul Supporting Member Supporting Member

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    Check the wiring around that sender for the idiot light, better yet remove it and replace it with a sender for a real temp gauge
     
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  5. Richard Clasby

    Richard Clasby Registered User

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    I'll check that wiring and update you. Thank you.
     
  6. nostrokes

    nostrokes Registered User

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    If he pulls the sender and leaves the wire off wouldn't it keep the engine light on?? I had issues with my oil psi gauge and if I left the wire off the engine light stayed on. I know the oil psi gauge would be different because it's looking for feedback for the light but not sure about the temp.
     
  7. Cubey

    Cubey Full Access Member

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    The factory oil pressure gauge triggers the engine light at idle if it drops down to the bottom line. A previous owner put a mechanical oil pressure gauge so I know it’s a false alarm. In fact that’s why they put the proper gauge, so I was told. I just ignore the light.
     
  8. Richard Clasby

    Richard Clasby Registered User

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    I just pulled the sender wire off and cleaned it...after putting it back on the Temp Gauge started working (went back to the middle) and the light stayed off. I'll drive it later and see if it acts up again but for now it looks like it was just dirty. Thank you!
     
  9. Thewespaul

    Thewespaul Supporting Member Supporting Member

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    Nope the switch there is normally open so nothing to worry about there.
     
  10. icanfixall

    icanfixall Official GMM hand model

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    The way these coolant sensors work is the one in the drivers side front of the head is normally open but..When your coolant reaches 242 degrees it will send the dash gauge needle well past the "L" and turn on the light.They do fail. Easy to lift the wire and not worry about it.,To test if this sender is bad remove the wire on a warm or cold engine. Ground the wire and watch the dash temp gauge swing over to the well past "L" letter. The normal dash sender is located just above this sender on the flat of the block. They work together.If you remove this wire the dash gauge will not work. Not sure if a light comes on or not. Try doing some tests and post back what you find out.
     
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  11. Thewespaul

    Thewespaul Supporting Member Supporting Member

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    I have my idiot light removed and my dash gauge works the same as before
     
  12. Cubey

    Cubey Full Access Member

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    My factory temp gauge stays around N and O at full operating temps.

    The one time it got to the middle, before I had a real temp gauge, I was stuck in mud (2wd) so I kept going forward and back as quick as possible. I bet it was close to being too hot for these engines. (240).

    I installed my aftermarket temp gauge sensor in the dummy light sensor hole, leaving the factory gauge sensor hooked up. It doesn’t force the engine light on to have nothing hooked to the sensor wire.
     
    Last edited: Dec 7, 2017 at 7:00 PM
  13. Richard Clasby

    Richard Clasby Registered User

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    Sooo the update is that now the (after cleaning the sender) the temp gauge works great. No more idiot light so Thank you! You pointed me in the right direction. It's nice to have a "win" every once in a while.
     
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