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  1. #11
    Master Mechanic zigger215's Avatar
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    I was an electrical tech. This isn't a guess . I'm trying to save him some money. This is very common on these trucks, standards auto techs know very little about the electrical systems of a CAN GM vehicle.

    There is no such thing as "reverse current flow.." Especially considering current in a DC circuit flows from negative to positive. Current leakage in a DC system is actually defined as a few different things. The most common form of leakage in or systems would be known as a parasitic draw. Even the worst parasitic draw would NOT be causing the issues he is having.

    Another thing, bad alternators affect every aspect of the vehicles electrical system. If it was truly a bad alternator, the truck would possibly have cranking problems, problems when he revs it to 2000rpms and a host of other minor problems which I'm assuming the OP would have posted.

    His issue is not the alternator and not the battery. He does have a parasitic draw somewhere because his battery died after Acouple weeks of being gone. He needs to relearn the idle and then he can begin tracking down the parasitic draw which could be as simple as shorting of two plates in the battery itself. Even so, a two week time period to kill a battery isn't the end of the world, most of our trucks WOULD probably have a dead battery after two weeks. Once this has been introduced into your trucks electrical system (which our is primarily made up of negative triggered computers) then little things like forgetting how to idle start happening to our trucks
    Last edited by zigger215; 01-21-2013 at 09:51 AM.

  2. #12

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    Hasn't gave me trouble anymore since yesterday but I am going to get the alternator checked and I just went to go get a new battery.

  3. #13
    Master Mechanic zigger215's Avatar
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    Your issues are gone my friend. Idle just had to relearn itself. I would hook a shunt up to your battery and see what the draw is. Do you have an electrical mods on the truck?

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  5. #15
    Master Mechanic zigger215's Avatar
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    What are the mods?

  6. #16

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    Ziger is right, every time I disconnected and then reconnect the battery to my old 2003 Astro, the engine would run like crap for a minutes or two then smooth right out. Starting was also a little difficult until the relearn process was completed.

  7. #17
    Master Mechanic zigger215's Avatar
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    Our silverados have a longer relearning process but it is the same as you had to deal with on your astro

  8. #18

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    My 01 did this but took about a minute of high idle with my foot and it was good to go. The reverse flow he was talking about might be when a diode or 2 goes bad and you get some ac in the charging circuit.

    Talking about bad for the engine ever do a cam/ crank relearn on a gm? Hold the pedal to the floor for 15 seconds, sounds like its gonna blow scarry as sh*t.
    01' 1500 LT Z71 ECSB 5.3L
    line-x'd front brush guard with KC Daylighters, 6000k HID lows and highs, rewired highbeams, Trans-go mild shift kit, custom stainless duals, 3500 dually OEM taillights, K&N CAI. Still have OEM fender flairs and leveling kit in boxes waiting for time.


  9. #19
    Master Mechanic zigger215's Avatar
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    How would a failed diode cause DC to be inverted to AC? That's not possible. The only thing a failed diode would do is cause current to travel down a path that the engineer tried isolating with a diode. This wouldn't be considered "reverse" it would just be an alternate path back to the positive side of the battery (negatively charged electrons want to go home, their home being the positive terminal of a battery). It's not possibly to reverse the flow of current in a DC circuit without somehow changing the atomic structure of an electron.

  10. #20

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    Quote Originally Posted by zigger215 View Post
    That's not what it is trust me lol I have worked on the electrical systems on more silverados than I can ever even try and remember. You'll replace the alternator and then be pissed when the problem is still there. Take your truck for a good long highway drive.
    My 02 used to do the same thing. After working on it with the battery disconnected it would hardly idle. It would stall when rolling up to a stop sign. After driving it on the freeway for a few miles it would return to normal

    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, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

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