need help with flickering headlights!!!

Discussion in 'GM Electrical Tech' started by redneckarmyMP, Aug 30, 2012.

  1. redneckarmyMP

    redneckarmyMP Epic Member 5+ Years 500 Posts

    Hey guys, I recently noticed my headlights and dash lights flickering while im driving down the road. I dont really have a lot of electrical accessories in the truck. I have HIDs for low beams, stock high beams and (4) Hella lights on the brush guard which i do not run often. I have also noticed the interior lights dim and voltmeter drop from 14 to about 9 when I roll my windows up.

    Just trying to get an idea of where to start before I start throwing money into it. Im not sure when the battery was replaced but I put a new alternator on it less than 2 months ago. Help! This is driving me crazy! Thanks!!
  2. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    Is it only while driving or does it manifest at idle, too? How about if you're parked but applying throttle?

    I'm asking because if it's only while driving it suggests a loose connection ... whereas if it does it at idle or while revving and stopped it could be the alternator.

    I'd certainly check the alternator, engine ground, and battery connections (including the red positive junction box near the alternator) and make sure they are all clean and tight, just for good measure -- regardless of the moving/non-moving bit. If all connections were tight I'd next apply a meter to the alternator if I could reproduce the problem while not moving ... and make sure it's output was consistent.

    Hopefully those basics help...
    Last edited: Aug 30, 2012
  3. Skippy

    Skippy Member 2 Years 100 Posts

    If you can't find the failure point, just tell people its a safety feature, when you sell the vehicle. People notice you better with flickering lights. LOL

  4. moogvo

    moogvo Epic Member 5+ Years 1000 Posts

    Check the small ground wire that goes from the negative battery terminal to the body of the truck. That is most commonly the failure that will cause that to happen. If that is secure, move on to other grounds. you have a bad one someplace.
  5. dobey

    dobey Epic Member 5+ Years 500 Posts

    You installed HID bulbs in the factory reflector housings? Did you use a cheap 55w HID kit with the big ballasts? I bet if you plug the factory bulbs back in and take the HID stuff out, it will stop flickering. It's a common problem with many HID installs.
  6. redneckarmyMP

    redneckarmyMP Epic Member 5+ Years 500 Posts

    It does it at idle as well as driving. It begins as soon as i start the truck. The HIDs have been in since 2007 so I dont really suspect them. Especially since its not only the headlights that flicker. My interior cab lights, as well as the intrument cluster and radio flicker. As far as I can tell, nothing in particular causes it as far as idle, higher RPMs, in gear or park. The fact that my voltmeter drops considerably while trying rolling up or down my windows makes me think it may be time for a new battery? I suppose it definitely wouldnt hurt to check my ground wires.
  7. Enkeiavalanche

    Enkeiavalanche Loving the Outdoors Staff Member 5+ Years ROTM Winner 5000 Posts

    On a lot of new GM's you need to use a relay for the headlights if you hook up HID's.. Was this done?
  8. dobey

    dobey Epic Member 5+ Years 500 Posts

    You didn't mention in the OP what year the truck was or how long ago the HIDs were installed. You might want to check your ground wires (do the big 3 upgrade if you haven't), and also check your alternator and battery.
  9. The Heater

    The Heater Rockstar 100 Posts

    The voltmeter on your dash tells you when there is an imbalance between the output of the alternator and that of the battery. First place to start is with the battery. Do you have a good battery charger (one that will run a float or maintenance charge of around a half amp when the battery is fully charged)? Simplest first step is to fully charge the battery. Lots of potential issues with batteries, but for this post, just saying to charge it. If you have a battery tester, great, test it. You can buy battery chargers that run tests on the battery and tell you its status. They cost more, but I have one and am glad I do. In any event, assuming your battery is good and it will hold a full charge, then see if a fully charged battery still causes the problem you describe.

    If you still get this information from the volt meter, I would have the alternator tested if you don't have a way to test it yourself. There are some voltage readings you can take with a simple volt-ohmmeter, off the battery with the engine running at certain speeds, don't have those values right here, or you can also buy a battery tester like one from Snap On (what I have) or another maker, and use that.

    The simple equation is that the voltage gauge is telling you the alternator is unable to keep the balance between it and the battery output. Could be something is wrong with the battery, the alternator, or you have some place that is taking power (or you have poor contact for the ground for the battery).
  10. redneckarmyMP

    redneckarmyMP Epic Member 5+ Years 500 Posts

    Well I broke down and bought a yellow top Optima battery last week. Havent had any lights flicker since then and the voltmeter hasnt been bouncing back and forth whenever i push a button. Thanks for the input guys! If something changes I'll be back for more help!

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