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Dimming Head Lights Help ?

Discussion in 'GM Electrical Tech' started by Mainefirefighter, Mar 17, 2013.

  1. Mainefirefighter

    Mainefirefighter New Member

    Hey all, I have a 2004 GMC 2500HD Crew Cab Duramax and every now and then the head lights will dim almost like they do when your anti-lock's kick on. I have replaced both battery's and put a new high output alternator on the truck and i am still having issues with the head lights dimming. Also it's not showing any defect codes on the computer.
  2. RayVoy

    RayVoy Active Member 1000 Posts

    I suppose this only happens when the truck is being driven. What will the voltage gauge do when this happens?

    Are you saying, every thine the ant-lock brakes kick in the headlights dim?
  3. Enkeiavalanche

    Enkeiavalanche Moderator 1000 Posts

    What else is in the truck? Lights, Stereo, inverter Eta???
  4. Mainefirefighter

    Mainefirefighter New Member

    Only when im driving, nothing major except some led's but even when the master is shut off to all the accessories it still dose it.

    - - - Updated - - -

    yes no voltage gage movement and the antilocks dont feel or sound like they come on
  5. Enkeiavalanche

    Enkeiavalanche Moderator 1000 Posts

    Check all grounds first You said you up graded the Alt? What did you go with? Did you upgrade the Wires too?
  6. Mainefirefighter

    Mainefirefighter New Member

    it did it before i replaced the alt and battery's too and all grounds are fine
  7. Enkeiavalanche

    Enkeiavalanche Moderator 1000 Posts

    You did the Big 3? Main grounds and Power wire?
  8. Mainefirefighter

    Mainefirefighter New Member

    Correct, iv been thinking would a bad wheel sensor be triggering the anti locks just enough to dim the lights ?
  9. RayVoy

    RayVoy Active Member 1000 Posts

    Anti locks should not be dimming the lights. You might have an internal problem in the ABS computer that is overloading the electrical.
    Pull the ABS fuse, see if the problem goes away.

    And a note, a bad wheel sensor will normally turn off the ABS
  10. Mainefirefighter

    Mainefirefighter New Member

    Had the whole ABS computer replaced cost me $600 installed and it did it before and after

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