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Strange headlight happenings

Discussion in '40- & 55-Series Tech' started by Vortec_Cruiser, Jan 2, 2003.

  1. Vortec_Cruiser

    Vortec_Cruiser

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    I had a strange thing happen to the headlights on my 1977 FJ40. When I pulled my headlight switch to the first notch (running lights position) my headlights would come on. When pulled to the second notch (normal headlight position), my high-beams would come on. After much testing, I found that removing the high-beam-indicator bulb from the instrument cluster would cause the headlights to again function normally. I noticed that a portion of the printed-circuit board in the instrument cluster appeared to be scratched, and thought maybe this was the cause of this strange behavior. Whether the printed-circuit is, in fact, scratched through is uknown. Anyone have any ideas on this???

    Ed Gilbert - TLCA #5659 ::)
     
  2. Gumby

    Gumby Supamod Staff Member s-Moderator

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    I've checked out the wiring diagrams and this is a goofy one. I'm thinking that you have a bad ground. The wiring diagram looks like the front fender lights and the head lights use the same ground. The power is feeding back through the light switch and finally through the high beam light when the bulb is in. When it's not maybe the power is backfeeding thought the rear lights.

    The light switch and/ or the high beam switch could be causing the problem too, but that's really weird.

    Good luck, Ed
     
  3. Vortec_Cruiser

    Vortec_Cruiser

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    I had checked the light switch and the high-beam switch, and both are functioning properly in their circuitry.  I'll double-check for a bad ground.

    Thanks,
    ::)
     
  4. teat

    teat

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    real strange
     
  5. edwjmcgrath

    edwjmcgrath

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    This sounds like classic bad ground/backfeeding. The fact that it changes with the indicator light is a smoking gun.