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  1. #1

    Default Something draining the battery.

    Hey Guys,
    I have a issue with my 2003 Yukon. While it's idling the Voltage is 14v, but when you start driving you can see the voltage drop until the engine dies. I already replaced the battery and the alternator. When I restart the engine, I can let it sit forever and it will read 14v, but when I start driving it will kill the battery again. Any Ideas?

  2. #2


    Yust becuse you already has replaced your bat and alternator dosent exclude them from being broken ,, your scenario looks like a thrue alternator problem ,, what happends with the voltage if you rev the engine standning still ? and has you checked your connections ? is the alternator HOT and finaly what happends with your voltage if you idle and starts heavy consumers ( fan , wipers , headlights and so on ?) and same scenario but rev the engine to 2000 rpm ?

    BTW how does you restart the engine after it goes down with zero on the voltage meter ??

  3. #3
    stephan's Avatar
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    Sep 2010
    Far West, Oregon USA,
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    X2 on 2 louds advice. Did you have the old alternator & battery checked before you replaced them? Assuming your new alternator is good, this sounds like a chassis or alternator ground problem. Check them & clean them. They need to be clean & shiny, no rust & no corrosion. Also make sure your alternator is 100% grounded to the engine. If your alt ground is marginal due to paint, rust or corrosion, it will charge fine at idle, but like 2Loud says as soon as you start driving it with consumers sucking the life outta the battery, the alt won't be able to keep up.
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