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  1. #1

    Default is it electrical problem

    Help please, I have 2007 Gmc Sierra 1500, about two weeks ago my truck was flashing battery not charging it did it for a few days before it died. So my husband thought it was the alternator so he had that tested as well as battery. The battery came back bad alternator came back fine. So put brand new battery, now today its doing it again reading battery not charging now my truck it dead. please help I need my truck

  2. #2


    did they test the alternator on the truck or off of it? Some of the alternators from the trucks with the Variable charging system (will have a big black box on negative battery cable) Will be damaged if removed from the truck and tested on the bench. From the way I understand the variable system, the pcm or bcm tells the alternator how much amperage and voltage is needed at any specific time. By running one of these alternators on a test bench they are running unregulated and damaged. Many parts store websites even say in the description for the alternator, "test on vehicle only". Unfortunately, most of the guys at the chain stores don't know this and bench test them.

    My suggestion, if you end up buying an alternator, is to buy a new one. DO NOT under any circumstances buy a rebuild or reman. I (and many others) have had nightmares with a rebuild. I went thru 6 in 2 months before I broke down and spent the extra $30 for a new one. Also, check and see if yours is a Bosch or a delphi. My year offered 2 different brands of alternator and 2 different amperage (so a choice of 4 different alternators) and from what I have been told, the brands are not interchangeable but amperage is.
    Last edited by Pikey; 04-16-2014 at 11:19 AM.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  3. #3


    yes my husband took the alternator off the truck and took it in. Would it work for a couple of weeks before if it went bad from removing ?

  4. #4


    Quote Originally Posted by klynn View Post
    yes my husband took the alternator off the truck and took it in. Would it work for a couple of weeks before if it went bad from removing ?
    when I have seen them fried it was immediate. maybe, it was on it's way out last time causing intermittent issues.

  5. #5


    Hi klynn,

    I am sorry to hear that you are experiencing an issue with your vehicle. As a customer service representative, I'm not able to provide much in the way of do-it-yourself information, so I'm glad to see forum members are beginning to step in with feedback. If you have any lingering concerns please contact me via private message.

    Jennifer T.
    GM Customer Care

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