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Temperature Gauge Not Registering

Discussion in 'Electrical Systems' started by Kent LaBerge, May 23, 2020.

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  1. May 23, 2020 #1
    Kent LaBerge

    Kent LaBerge Member

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    '70 Z28 temp gauge has not been working, but feel i should tackle it this year. Gauge is new as is the wiring. When I turn on the ignition the needle moves fully to the right and then drops back to left and doesn't register any temp. The movement of the needle is exactly what I have read when u want to test the gauge, ie, turn on the ignition and ground, needles moves to right it to indicate gauge is okay?
    So what is my problem when it does that with grounding.
     
  2. May 23, 2020 #2
    wnmech

    wnmech Veteran Member

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    It’s been awhile but I’m thinking that there may be different temp switches into the head maybe you have a sending unit for a light versus the gauge. Don’t quote me for sure no that. Also when you installed the sending unit into the head did you use thread tape? Maybe the sending unit needs the head for a ground.
     
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  3. May 23, 2020 #3
    COPO

    COPO Veteran Member Lifetime Gold Member

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    When I used my factory temp gauge in my 70 Z28 and turned the car on, the needle is not suppose to move until the coolant starts to get hot. It should not swing to the right then back to the left on startup. You definitely have a problem.
     
  4. May 23, 2020 #4
    Kent LaBerge

    Kent LaBerge Member

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    No I didn't use tape.

    In response to COPO , can't someone tell why then is the needle moving as it is upon ignition?
    Thx
     
  5. May 23, 2020 #5
    COPO

    COPO Veteran Member Lifetime Gold Member

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    Maybe this will help.
     
  6. May 24, 2020 #6
    Kent LaBerge

    Kent LaBerge Member

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    Thanks, COPO, that is what I needed to hopefullly resolve my issue. Funny, but it was American Auto wire I used to wire my car but didn't come across this video. This should be my last resort as I have rechecked all wire connections, correct wire to correct location, even removed the printed circuit and traced the paths thru tot he gauges.
     
  7. May 24, 2020 #7
    Kent LaBerge

    Kent LaBerge Member

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    I reviewed the video and before I get doen to actual testing I can't think how one test can be done since the gauges are not hardwired but contact runs thru the printed circuit. So to test the gauge the advise was to remove the sending wire from the back of the gauge and then run jumper wire to ground. How do u do this with the printed circuit? I'm at a lost which sometimes isn't hard to do.
     
  8. May 24, 2020 #8
    dave@ztech

    dave@ztech Veteran Member Lifetime Gold Member

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    I think they mean to ground out the sender not the gauge
     
  9. May 24, 2020 #9
    COPO

    COPO Veteran Member Lifetime Gold Member

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    I would remove the wire from the sending unit and ground it.
     
  10. May 24, 2020 #10
    Kent LaBerge

    Kent LaBerge Member

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    Grounding the sender will test the sending unit so once that is tested then I can test the gauge.
    As suggested by COPO removing the wire from the sending unit and grounding that would be the same as grounding from the back of the unit to test the gauge. This should set me on the right track.
     
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