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Thread: Persistent Battery Drain - Any fresh ideas ?

  1. #1
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    Persistent Battery Drain - Any fresh ideas ?

    RS6 with a persistent 2.9A drain, measured with an ammeter on the battery.
    Spec is it should be less than 0.5A

    When locking car it's still there, it will run flat overnight unless kept on charger

    Pulled all the fuses in the side panel - no difference
    Pulled all the relays under the drivers kick panel - no difference
    Pulled the ECU (as much as can with half the connector effectively welded on) - no difference

    Gave it to experienced Audi Dealer with veteran tech - no clue.

    Anything am missing ?

  2. #2
    Registered User hahnmgh63's Avatar
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    You've pretty much done what any good troubleshooter would do. Any aftermarket accessories? Alternator going bad? Try disconnecting the power leads under the windshield cowl on the passenger side one at a time and see which one drops the current, then reverse trace that big lead.
    2003 White RS6 BBS RS-GT, RNS-E, KW V3's & Hotchkis
    2001 225bhp tt roadster 2x944 Turbo's 1974 911 w/'91 3.6ltr motor
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  3. #3
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    Which big wires are you speaking of ?

    Only saw one from the Battery (hard line from the trunk) in there.
    It's splits into alternator and the rest - are you saying separate those two from the battery line ?

    Welcome suggestions for any other major hard line taps to try ?

    Alternator is good, tested and works well.
    Have a flashed ECU, perhaps that's not properly putting car into sleep mode ?
    Or perhaps the comfort/locking module ?

  4. #4
    Registered User hahnmgh63's Avatar
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    Yea, that's what I'm thinking. Separate the lines and check the resistance and see which one has the least to ground.
    2003 White RS6 BBS RS-GT, RNS-E, KW V3's & Hotchkis
    2001 225bhp tt roadster 2x944 Turbo's 1974 911 w/'91 3.6ltr motor
    Roy, WA

  5. #5
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    Make sure your hood switch is reading closed when the hood is closed. Number 1 problem I see with the C5's having a battery draw.

  6. #6
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    Quote Originally Posted by canyon View Post
    Make sure your hood switch is reading closed when the hood is closed. Number 1 problem I see with the C5's having a battery draw.
    Hang-on, if hood switch wasn't closing properly then the car wouldn't beep when all locked from the remote.
    Correct ?

    Mine beeps just fine - so central locking must be reading everything closed including the hood.

  7. #7
    Registered User lswing's Avatar
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    I thought you could lock and arm without closing the hood all the way? You on original battery still? Could it be the battery simply isn't holding a charge and draining? Any work or anything new done?
    Ace/Edge TC - Tozo Trans - MTM TCU - REVO/ME7 tune - Wagner IC's w/ Venair Hoses - Aux Radiator delete - Hotchkis Sways - Hawk HPS Pads - Koni Sport Struts - Scroll KO4 Turbos - Devil's Own WM - 421whp/452wtq on Mustang Dyno - http://www.audirssix.com

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