Low Voltage, Dimming lights.

Discussion in 'GM Electrical Tech' started by 03HeavyHalf, Feb 17, 2011.

  1. 03HeavyHalf

    03HeavyHalf Rockstar

    Alright, i got a 03 1500hd, 6.0. When i accelerate, the volt meter drops to about 9, my lights will be almost off, but when my truck shifts to the next gear the volts come back up and the lights get brighter again. I had the alternator checked but nobody can seem to say whats wrong with it. any help is awesome.
  2. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    something i would try is have the battery load tested, and check the chassis grounds to be sure they arent loose.
  3. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner 1000 Posts

    these were things I was going to suggest. Also maybe (just a guess), the regulator on the alternator could be going bad. most new ones are internal so a new alternator would be needed. but do the original suggestion first as it is free.
  4. dualdj1

    dualdj1 Rockstar 100 Posts

    actually from what I was told most of the new ones are regulated by the computer (could be wrong, but that came from a GM mechanic). And barring grounding/other electrical issues, I could see that as being likely in your scenario.

    I think your most likely culprit though is a ground/connection issue.
  5. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner 1000 Posts

    ha, guess I'm a little out of date on new. A day late and a dollar short. :rofl:
  6. dualdj1

    dualdj1 Rockstar 100 Posts

    No Worries, the only reason I knew was I was digging for alternator compatibility info, and i think it's about mid/late 90's on they use external regulators (through the computer).

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