Gauge cluster illumination and grounding

Discussion in 'General Automotive Tech' started by bambusbjoern, Oct 19, 2017.

  1. bambusbjoern

    bambusbjoern Active Member

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    Hi there!

    Today i've tried to fix my weak gauge cluster illumination. Some areas are working (but poorly), others are completely dead.

    First thought: Bulbs. I removed every bulb from the cluster but all of them are fine despite the age.
    Second thought: Dimm switch. The old one was almost broken, so i replaced it - no change there.

    I did some research and found out that sometimes a bad grounding of the cluster could cause the problem.
    I'm not an electrical guy and i can't figure out how that damn thing is grounded. There is a big connector (pic) behind the cluster...maybe one of the wires is ground?
    Additionally, the circuit board looks like it's damaged. Probably that is causing the problem (too).

    Maybe you guys can help a bit.


    Greetings from Germany.
     

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  2. elB

    elB Well-Known Member

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    The spring metal connection on the light bulb socket loses its "springy-ness" or corrodes and both situations result in no connection for the bulbs to work. If you're in that boat, try replacing the bulb sockets with new ones (ACDelco and others still make them new).

    A bad ground would likely be indicated by NO functionality on that particular part of the circuit: you wouldn't often get some bulbs working and others not in the same circuit (lights) with a bad ground.
     
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  3. bambusbjoern

    bambusbjoern Active Member

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    Mh, the sockets look and feel good, but I'll test them.
     
  4. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

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    Get a brass-bristled brush (looks like a toothbrush but you don't want to brush your teeth with it) and give all the contact areas a good gentle brushing (so as not to damage the foil runs) as well as the contacts on the sockets. The cluster will have a ground wire or two; if the ground connection is dirty or corroded, that will make the bulbs dim, but you would need a Pontiac factory manual for the wiring diagrams and ground wire locations. Also, get under the hood and clean all the ground wire connections that provide the body's ground path: the 'strap' between the firewall and cylinder head, and the cable between the engine block and battery negative.
     
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  5. bambusbjoern

    bambusbjoern Active Member

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    I can really brush the copper-foil around the area where the socket is inserted? It looks and feels very vulnerable.
     
  6. OldFox

    OldFox Curmudgeon

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    It is fragile. Use a pencil eraser instead. You have more control.
     
  7. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

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    Depends on the eraser. It has to have coarser abrasive, otherwise, I've found erasers to generally be ineffective. But I had to do the remedial cleaning on my Ranchero's cluster just to get the lights to come on, including replacing sockets, and that cleaning required the brush because of the corrosion, but I did not da.age any of the foil runs.
     
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  8. bambusbjoern

    bambusbjoern Active Member

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    Ok, i'll try that, but first i have to pull the cluster out of the dash, things will be easier then.
     
  9. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

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    That would help.:bigsmile:
     
  10. bambusbjoern

    bambusbjoern Active Member

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    Today i've tried to change some ground-wires in the engine-compartment but i failed.
    Anyway, i've found something in the fuse box: the same cylinder as shown in the pic (pic is not mine but it looks the same) with one single wire on it...but it's not plugged to something. I have no idea what that is and where it should be.

    Can anybody help?
     

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  11. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

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    Interesting. It's a condenser, what we over here call a capacitor, but it's usually found where electrical 'noise' interference comes from, such as the ignition coil or the alternator. In all my years of experience, I have never seen one on a fuse box, but perhaps there is noise coming through the electrical system somewhere?
     
  12. elB

    elB Well-Known Member

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    Noise suppression capacitor. Added as part of the radio package on these cars. It's not the source of your dim dash lights.
     
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  13. bambusbjoern

    bambusbjoern Active Member

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    Maybe it's not the source, but I'm getting nervous when something that should be connected to somewhere is not :D
    Thx for help.
     
  14. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

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    Interesting. I have never seen one installed right there in the fuse block. Usually, it'll be in the harness, right next to the 'noise generator.'
     
  15. bambusbjoern

    bambusbjoern Active Member

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    Here's a pic out of my manual where it is located. Unfortunately it was without a description.
     

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