Intermitent blinking battery light

Discussion in 'General Chevy & GM Tech Questions' started by thejms, Aug 14, 2010.

  1. thejms

    thejms Rockstar

    I have an '02 GMC Sierra 2500HD with the 6.0L

    I was on a long road trip. Out in the middle of no where my battery light started intermittently going on and off. I immediately checked the volt meter. It was normal at 14v. I keep driving. They light eventually stopped coming on. About 150 miles later the light started doing it again, this time the volt meter had dropped about 2-3 volts. I was still about 120 miles from home so I turned off my stereo, my AC, and didnt even use cruise control. I was determined to make it home. I made it home but before I stopped at Schucks and had them run there charging system test. All they could tell me was that I had 11v at my battery and it needed to be charged. I made it home. I pulled out the alternator and had it bench checked. They guy at Napa said that it was bad so I replaced it.

    After I replaced it I thought that would fix the problem but it didnt. I just got the new aternator installed and went for a short drive. The battery light is still intermittent. The volt meter in the truck reads 14. When I hook up the multimeter it reads 13.8 with no accessories running. When I turn on everything, AC on max, Stereo and Lights on bright, it drops down to 13.1 but never drops lower. So the alternator is working but what could cause the battery light to be intermittent. When I say intermettent I mean that it comes on for 3 seconds, goes out for 5, comes on for 2 seconds, going our for 3. Its always coming on but never in a constant pattern.

    The battery was diconnected from my truck form about 3 days so I would assume that would of cleared any codes that was in the system.

    Any suggestions? Should I not drive it? I'm pretty stumped
  2. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Hmmm have your battery load tested if you dont have a load tester. There is a chance that it has a bad cell.... Otherwise you really have me.. I know that i had a pin push out on my 06 Silverado that caused the same thing. So I would start there if your battery is good to go.
  3. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Have you had the battery load tested since you changed the alternator?
  4. thejms

    thejms Rockstar

    What do you mean by had a pin push out?

    I havent had my battery tested yet. I'll have to do that tomorrow. I am home with the kids now. Thanks for the suggestions. I'll update when I get the battery tested.
  5. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    This was a dealer repair at 400 miles.. anyhow supposedly the wiring harness that pluggs into the Alternator had a pin that had pulled/pushed out so there was no contact on the plug.
  6. thejms

    thejms Rockstar

    Oh ok I see what yours saying.
  7. thejms

    thejms Rockstar

    Brought it in today to have the charging system checked again. They say that the Battery and Alternator are both good. They say the only thing that was off was when I went to start my truck my battery was at 10v. It didnt seem hard to start or anything. Drove it most of the day. Light is still intermittently on and off. Mosty on. Volt meter never dropped at all. Didnt get to have the codes pulled if there are any, I guess someone borrowed Schucks reader and neglected to return it. Got a friend that is going to check to see if any are stored tomorrow.
  8. thejms

    thejms Rockstar

    Is everyone pretty much as stumped as me on this one? I have driven it since I replaced my alternator. I havent noticed anything abnormal except the battery light keeps coming on.
  9. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    YEAH i sure am.. Sorry man. Did you check the wiring harness etc? As i mentioned, that really is the only place i can think unless you have a short in the cluster.. Which is possible. Otherwise everything works like it should sooooo...
  10. thejms

    thejms Rockstar

    Buddy just pulled some codes, I had 3.


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