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Thread: Fog light/headlight wiring issues

  1. #1
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    Fog light/headlight wiring issues

    So I put new LED headlights in and now my fog lights aren't getting any volts to them, but the switch is fine. I suspect it has something to do with the headlight circuit and how the new headlights function. It took some figuring out to get the LEDs to function in the same way the stock headlights work as in the low beams staying on when you switch to high beams. I have that part figured out the best I can. I haven't altered the stock headlight harness at all, just re-pinning the LED headlights. When just the low beams are on, the high beams are receiving very minimal voltage, so they are lit but not enough to really tell. I think without the LEDs being dual filament as in the stock sealed beams is throwing something off in the circuitry and causing the fog lights not to receive voltage since the car is seeing slight voltage to the high beams. Any thoughts?


  2. #2
    Van Fan VanCo's Avatar
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    Re: Fog light/headlight wiring issues

    I just installed some LEDs too. I'm not satisfied with the electrical portion of it though. I read the schematic and LEDs really aren't compatible out of the box. The van headlights have a single power wire and negative switched high and low beam. This is backward from how the LEDs are wired. In addition the high beam indicator and fog light relay require a positive signal backtracking from the headlight filament for power. LEDs do not provide the resistance necessary to light the incandescent dash bulb, or trigger the fog light relay. I'm planning to install 4 relays, one for each bulb (behind the dash) to swap the negative to positive and provide the proper positive power to the high and low beam, dash bulb and fog light wire.

    I'm pretty sure this is why your fog lights don't work.

  3. #3
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    Re: Fog light/headlight wiring issues

    Quote Originally Posted by VanCo View Post
    I just installed some LEDs too. I'm not satisfied with the electrical portion of it though. I read the schematic and LEDs really aren't compatible out of the box. The van headlights have a single power wire and negative switched high and low beam. This is backward from how the LEDs are wired. In addition the high beam indicator and fog light relay require a positive signal backtracking from the headlight filament for power. LEDs do not provide the resistance necessary to light the incandescent dash bulb, or trigger the fog light relay. I'm planning to install 4 relays, one for each bulb (behind the dash) to swap the negative to positive and provide the proper positive power to the high and low beam, dash bulb and fog light wire.

    I'm pretty sure this is why your fog lights don't work.
    The best I made it work with the stock wiring is:
    1: Fog lights on all the time, the fog light switch also controls the low beams on or off, everything works as normal if you leave the fog lights on. If you turn the fog light switch off you lose low beams and fogs.
    2: No fog lights at all, and high + low beam function as normal.

    I think #2 is the best option and Iíll simply create a dedicated, related circuit for the fog lights. I donít want to alter the stock wiring at all because Iím not great with wiring and these vans are already plagued with wiring issues.

  4. #4
    Van Fan VanCo's Avatar
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    Re: Fog light/headlight wiring issues

    To avoid electrical issues either the incandescent headlights should be put back in, or the wiring should be modified to send the proper voltage and signals to the LED headlights. The way the headlights are hooked up now is the definition of a "wiring issue."

  5. #5
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    Re: Fog light/headlight wiring issues


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