Dummy gauges not working

Discussion in 'Troubleshooting & Diagnosis' started by dhla, Feb 16, 2018.

  1. dhla

    dhla New Member

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    Feb 16, 2018
    Hi,

    I was working on my instrument cluster and the left-side "dummy" gauges (voltage and oil pressure) stopped working, that is, when I turn the key to ACC they don't illuminate as they should. The voltage light was very dim at first and then died completely.

    Might anyone have an idea, please, why this might have happened or where I should look? Specifically, what fuse controls these lights or where are they grounded from? Thanks!
    The bulbs are not burned out, and the other gauges and lights work fine.

    It's a 1972, base model gauges, no upgrades.
     
  2. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

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    Feb 26, 2004
    Bloomington, MN
    The background lighting is all on one circuit.
    The problem has to be with the printed circuit panel, sockets or the bulbs.

    Only one fuse (the little one) for the background light circuit.
     
  3. dhla

    dhla New Member

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    Feb 16, 2018
    Hi Twisted_Metal,

    The background lighting is working fine, as is the little 3A fuse that controls them. Are you saying that the lights which power the dummy gauges themselves (not the background) work on the same circuit as the background lighting? Thanks!
     
  4. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

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    Feb 26, 2004
    Bloomington, MN
    Sorry... I misunderstood the problem.

    The three indicator lights should all illuminate when you turn the key to ACC. (Oil, Temp, Gen)
    I believe that is a function of the ignition switch.
    If one works and the others don't, it is quite likely a problem with the bulb sockets not making a good connection with the printed circuit board.
    Or... Poor connections at the plug to the printed circuit at the rear of the cluster.

    Sometimes the copper contacts (where the plug meets the cluster) get loose and out of place while attempting to reconnect the cluster plug.
     
  5. dhla

    dhla New Member

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    Feb 16, 2018
    Ok, I'll give that a look, thanks very much for your help!
     

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