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  1. #1

    Default 03 1500HD 6.0 electircal gremlins

    hey all
    iv been having some power issues with my truck and its desire to die out on me. all the symptoms have pointed me towards there being an alternator problem while at idle dimming interior and exterior lights, interior fan speed slows down when a load is applied (stepping on the brake,hitting my power windows) the Volt meter goes from above 14 to around 10-11 then sometimes it will just die out. All of this of course goes away while im on the gas. Also very weird part is i can start the truck after it sits over night (even if its died) and let it idle for 15 min without any issues its once i get in and start driving even just down the block that the problems start. Just replaced the battery 7 days ago and then the alternator a few days later once it died again, got the alternator checked at the parts store today and they say its working perfectly on their bench tester. Parts guy recommended i charge the battery which im going to try to do tomorrow for a decent amount of time. The volt reading on a shut off truck battery is reading around 12.57-12.63 then up to 14.6 once its running. Also note that a remote starter/alarm was installed 4 weeks ago and the problems started 2 weeks ago. when i brought it back to the tech he said he couldnt find anything wrong with the starter system leeching more power and said he isolated that whole circuit and there was no problem he could find. im not familiar enough with wiring to start pulling things apart to figure it out on my own but would like to avoid the always pricey shop bills.

    any help would be great

  2. #2


    Where did you get the alternator? I had major issues with the brand advance auto sells. Went thru 6 in 2 months. A few had the same issue you are describing.

    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


    I got it from autovalue here In calgary its a "Quality built" rebuilt unit. Iv used these before in my Grand AM without any issues and the battery is a motomaster from the canadian tire. Remote starter/alarm is a compustar

  4. #4


    You might need to check your ground wires. Pull them off and clean the contact area and the cable ends. I started having a light dimming issue and hope to attack my grounds soon.

  5. #5


    sorry you will have to forgive my newbishness but out side of the grounding cable on the alternator im not really sure of where the rest of the grounding points are and theres nothing really in my haynes manual showing where they are. are they in the underhood electrical junction box located next to the battery? or can i at least follow something from there

  6. #6


    follow from the negative battery cable to the engine block and the frame. Also there should be some on the driver side of the fire fall area, connecting the body to the frame.

  7. #7
    Jr. Engineer Jamm3r's Avatar
    Join Date
    Dec 2012
    Minneapolis area


    Hi Zinger

    There are a few things to consider.

    Voltage change at idle becomes more pronounced in cold weather and as the battery ages. So depending where you are the weather may have something to do with it. This is part battery chemistry and part that the charging voltage is temperature compensated (the PCM does this) and is higher the colder the weather is, making for a larger swing.

    I believe your truck comes stock with an AD-230 small-frame alternator that doesn't produce as much output at idle as the AD-244. You could upgrade, it's an easy swap. I have the DR-44g, which is a cost-reduced AD-244, and it produces enough output at idle that there isn't any voltage drop.

    Check the condition of your battery terminals since corrosion or loose connections will make this worse too.
    Minneapolis area - 1997 K2500 regular cab long bed + 8.5' Western Unimount plow + modified transmission + 2nd battery + modified camper charge circuit + 1971 Cayo camper -and- 2004 4x4 Suburban 2500 8.1 + Maxbrake controller + 2nd battery + modified trailer charge circuit + Reese receiver, pulls 30' Airstream trailer

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