04 Peterbilt 379 no headlights

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by deanshaski, Aug 31, 2020.

  1. deanshaski

    deanshaski Bobtail Member

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    Jul 8, 2019
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    On the headlight switch it still turns the clearance lights on but not the headlights. Checked relays in the fuse box and the one in the dash. When switch is on it looses all power to the wire that had power when switch is off. No idea what to do
     
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  3. bad-luck

    bad-luck Road Train Member

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    I had a similar issue. Take out the relay in the fuse box. Then look at the fuse box it self. See if it is black and melted where the relay plugs in. 379's have an issue where the relays vibrate and cause heat and melt the fuse box where the relays plugs in.
     
  4. Just passing by

    Just passing by Road Train Member

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    I think this was a recall and Peterbilt has to replace the harnesses for both headlights.
     
    Last edited: Aug 31, 2020
  5. BoxCarKidd

    BoxCarKidd Road Train Member

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    Where exactly is this wire that losses power?
     
  6. FLHT

    FLHT Road Train Member

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    Ground the green wire in headlight bucket.
    The plugs under the Radiator may have corroded.
     
  7. Hawaiian Punch

    Hawaiian Punch Bobtail Member

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    Sep 5, 2021
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    [​IMG]
    [​IMG]
    Can anyone tell me if this headlight positions is legal?[​IMG]
    I don't see why not
    As long as you ajust them to the right flare, i don't see any problem.

    What y'all think?
     
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