Headlights dimming when i draw power

Discussion in 'GM Electrical Tech' started by Miller, Feb 23, 2011.

  1. Miller

    Miller New Member

    This started today,

    Truck is a 08 Sivlerado 5.3 4x4 extended cab 45k miles. It seems when I apply the brakes, turn signals, windows etc... the headlights dim for a split second and return to normal. Earlier it seemed the headlights would dim and radio go out for a split second when no brakes, blinkers etc were applied, but that seemed to stop happening after i was about half way home.

    Any ideas?
  2. stephan

    stephan Rockstar 4 Years 5000 Posts

    If your alternator is grounded properly, then this is most likely a bad chassis or body ground, or could be a bad connection in the main charging wire btw the alt & battery positive.
  3. drm223

    drm223 New Member

    hmm thats wierd tha happens on my new truck that has like 8000 miles
  4. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    Corrosion on any ground or power wire will cause a draw just like this, enough corrosion will even keep your car from starting. If you live an area with alot of salty, snowy, wet conditions or off roading/mudding this can be more common then you think. Start with what is free, check all the connections, make sure ALL the insualtion on the wires is intact and if you can take some readings, there could be a draw somewhere else that isnt strong enough to kill the battery. Eitherway your stock system as long as not modified should not be dimming or weakening during usage
  5. ntbush83

    ntbush83 Epic Member 5+ Years ROTM Winner 1000 Posts

    x3. I'd locate the source of your problem would be somewhere around or having to do with your alternator.
  6. Miller

    Miller New Member

    We'll it got really bad today. I got off early, cleaned up battery terminals, all ground connections I could find. The connections between battery, fusible link, alt wire and power wire seemed really bad, I was getting a lot of resistance across the fuse. cleaned everything up, took her for a test drive and it seems to be fine, so far. now onto my next issues!

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