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Headlights dimming and flickering. Heated seats not turning on

Discussion in 'General Chevy & GM Tech Questions' started by GMmonster, Oct 24, 2011.

  1. GMmonster

    GMmonster New Member

    Alright, so I'm never really worked on a lot of electrical problems, but this one is beginning to tick me off to a point I can't take anymore. When I roll my windows down or up, apply the brakes and even turn on my blinkers my headlights flicker and become dim. They also flicker when I crank my stereo up loud and my subs kick hard. The worst of it is when I roll my windows up or down and they become dim. I also recently noticed the other day that my heated seats no longer work. When I press the button the light for on comes up for a brief half a second then goes away. Anyone have any ideas as to why this is happening, and how I can fix it?

    I drive a 2003 GMC SIERRA 1500 ext cab, with a 5.3l Vortec and a Duralast yellow top battery.
  2. sstoner911

    sstoner911 Epic Member 5+ Years 1000 Posts

    You could have multiple problems. I would address the lights dimming and flickering first.

    Upgrade your BIG 3:

    Definition: the "Big Three" upgrade means improving the current capacity of three cables: 1) alternator positive to battery positive, 2) battery negative to chassis, and 3) engine ground to chassis. Some people replace the factory wiring; others add additional cables to the factory wiring.


    Couple questions:

    When did this start?


    Have you had the Alternator and battery checked? Is the alternator putting out what it should? Is the battery holding a sufficient charge?

    How do you have your amp wired for power and gauge of wire.
  3. The Heater

    The Heater Member 2 Years 100 Posts

    It could be as simple as a bad ground. Check that before you start spending money on a new alternator, etc.

    However, after you rule out the ground issue, if you rule it out, have a shop test the output of your alternator, or you can at least do an idle output test at the battery by using a volt ohmmeter. If the alternator works properly it should put out at least 13.4 volts or thereabouts, even with a load on it. Test with nothing on, then start turning stuff on like the heater, then the lights. See what the battery output is. If the voltage drops too low the seat heater will not turn on, I guarantee. It may have juice but if the voltage is not 12 volts or higher, it will not work.

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