Headlight gremlins- 99 VNL

Discussion in 'Volvo Forum' started by jayfarmlaw, Oct 31, 2022.

  1. jayfarmlaw

    jayfarmlaw Bobtail Member

    23
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    Dec 12, 2020
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    99 Volvo VNL, Cummins M11, Super 10, Single axle

    Left low beam was not coming on, wasn’t the bulb. Sometimes right low beam would stay on until you pushed the high-low/turn signal forward. Since pushing the switch forward solved the problem, I ordered a new switch.

    New switch, same problem…sort of. Still no left low beam, when you switch to high beam, both lights come on, but it will not stay in high beam. Let the switch go and it falls forward back to low beam and no left light.

    it’s an Automann switch and swap was easy plug and play witH no surprises. Did I get a bad switch or is there a light module somewhere that controls how high and low to stay on?

    Any ideas?

    Thanks in advance for your response.

    Jay
     
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  3. loudtom

    loudtom Road Train Member

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    I'm not sure if the older ones have a light control module, but my 2012 does and it will display faults on the dash like "left low beam circuit open" when there's an issue. If you're seeing those messages, you likely have a control module. I've had the headlights kind of rolling around inside the housing, I've had the ground pins melt the connectors from vibrating loose, and I've had pinched wiring near the hood mounts. I'd start with unplugging the headlight connectors and see if it's getting voltage. If you get voltage, troubleshoot towards the headlight, if not then troubleshoot towards the switch.
     
  4. DUNE-T

    DUNE-T Road Train Member

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    Detroit, MI
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    There is no light module on this trucks. I would check the fuses and light harness first
     
    jayfarmlaw Thanks this.
  5. jayfarmlaw

    jayfarmlaw Bobtail Member

    23
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    Dec 12, 2020
    0
    Well, after a lot of head scratching…..it turned out to be fuse F20. When Volvo says the F20 is left headlight, they really mean left low beam. High beam always got power….go figure. My dash is sent out for resoldering so I’m not back on the road yet, but both lights work as they should. Right light no longer stays on. I replaced the headlights with clear ones off eBay and the bulbs with some super bright led type that have little fans built in the bulbs. I’ll probably carry a set of normal bulbs with me.
    Thanks for the help,
    Jay
     
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