Electrical Temp gauge not reading correctly

Discussion in 'Classic Mustang Specific Tech' started by craig3x, Dec 11, 2012.

  1. craig3x

    craig3x New Member

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    the temp gauge on my '65 is reading hot, but I had a laser temp of the engine done and it's reading 178 degrees. Any ideas why it's reading incorrectly? Could it be an old brittle wire? Does resistance make it read hotter?
     
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  2. bartl

    bartl Member

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    The opposite. The more resistance, the LOWER the gauge reads. Sounds like a bad sending unit.
     
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  3. Jake2012

    Jake2012 Member

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    Agree with Bartl , I'm no autoelect but from experience most faulty temp gauge reads are caused by a faulty sender unit. Suggestion, not sure if you can test output of the temp sender unit ? If not, try changing the sender unit b4 doing other fault testing.
     
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  4. tx65coupe

    tx65coupe Active Member

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    What about the fuel gauge? It could be the instrument cluster voltage regulator. I have an electronic solid state one now. The only mechanical one I have had that works close to right is the original one.
     
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  5. 2+2GT

    2+2GT Well-Known Member

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    I agree. A couple years ago, I tested replacement senders from every manufacturer. Standard, Echlin, Delco, you name it. Ω was tested at 100°F. They all sucked, not even close. If you don't have an original Autolite or Motorcraft replacement, get one. They aren't available new, so you'll have to find one.
     
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  6. bartl

    bartl Member

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    The only other option is to find a resistor with the proper value to "calibrate" the gauge.
     
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  7. craig3x

    craig3x New Member

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    hmmm, I bought the car a few months ago, and it has a new intake on it and the sender looks to be new as well. My fuel gauge is accurate as far as I can tell, so I don't think its a cluster problem. Not sure what to do if all the aftermarket senders are crap as 2+2GT says
     
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