2005 379 headlight issues

Discussion in 'Peterbilt Forum' started by Cajuncowboy654, Jan 12, 2021.

  1. Cajuncowboy654

    Cajuncowboy654 Light Load Member

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    So I've been chasing a headlight problem on my 05 379.

    Since I bought it the drivers side light was dim on low beam and the indicator stayed on. I finally got it sorted out, the ground and low beam wire were swapped.

    A few days later, the same issue is happening, then the low beam on the driver's side was out completely, high beam works. Stopped down the road to check and all is fine.

    Tonight I'm running, and both low beams go out, high beams seem week.

    I'm guessing ground. Can anyone point me to where the ground is connected to the chasis for the headlights?? Or any other suggestions on what it could be?
     
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  3. Don379

    Don379 Heavy Load Member

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    I dont think your gonna find a ground to chasis. IT all goes into a harness to main harness. THe problem i see in my 379 with this issue is the plug that goes into the headlights. They are all corroded. Take a good look in the connections. Sometimes it cause my braker switch to pop. I was thinking about replacing the whole plug behind the headlight. you should probably do the same. Pull the headlight out and keep plugging in and unplugging the light while the light switch is on and see what happens and notice if the lights come back on
     
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  4. Cajuncowboy654

    Cajuncowboy654 Light Load Member

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    The plugs are clean. Checked them when I had it apart last week. Thats when I found the drivers side wires switched.

    Both low beams won't work now and the high beams are weak. Dont think its the plugs.
     
  5. Don379

    Don379 Heavy Load Member

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    well i can tell you, thats not good man. those wires go all the way to main harness. i would just replace the whole thing. but thats just me
     
  6. Luwi67

    Luwi67 Heavy Load Member

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    I'd wire each headlight direct to battery to verify they are functioning properly before chasing any possible wiring issues.
     
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  7. Cajuncowboy654

    Cajuncowboy654 Light Load Member

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    My plan is to is a test light to verify its getting power to the plug then if it is ill use a jumper wire from a good ground to the ground pole of the light and see if it works
     
  8. RocketScott

    RocketScott Medium Load Member

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    Check around the hood hinges. They are notorious for crushing the wires and causing problems

    Both headlight harnesses meet behind the bumper and plug into another harness that runs back to the pass through on the cab
     
  9. SmallPackage

    SmallPackage Road Train Member

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    Check Hi/lo switch on column.
     
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