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Alarm issues - No indicators when locked then flashing for no reason

Discussion in 'A3/S3 Forum (8L Chassis)' started by bradski, Mar 23, 2013.

  1. bradski

    bradski New Member

    Mar 9, 2012
    Likes Received:
    As above really folks, I've been away for 10 days, come back to my car and there is now no indicator when I lock it up. Everything worked fine when I left it, but when I lock it on the fob (and key in the door), the (silent) alarm goes off. No audiable alarm, but just the indicators and its not any door or window left open either.

    Anyone else had any similar problems?

    Any help appreciated, its going to be left unlocked tonight (don't try asking my address ;) ).

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  3. phil miller

    phil miller Well-Known Member
    VCDS Map User

    Sep 9, 2012
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    bonnet or tailgate catch dude, VCDS will tell you whats wrong
  4. Tooks

    Tooks Active Member

    Feb 20, 2006
    Likes Received:
    Sounds to me like your car is suffering from the quite common problem of the alarm siren circuitry being eaten away by leaking rechargeable batteries.

    I've owned three Audi's of this era now, and all of them have suffered this problem.

    Assuming VCDS doesn't flag up any sensor issues, you need to get to the siren down in the nearside rear boot compartment, remove it and crack it open. When you do so, you will probably find that the leaking batteries have corroded the circuitry in the siren, leading to all kinds of havoc.

    In mine, symptoms were lack of alarm confirmation lock beep, false activations, and no siren even though the lights were flashing. VCDS didn't help at all, no fault codes recorded.

    If the corrosion isn't too bad, you can sometimes clean the board up with contact cleaner, replace the batteries with some compatibles, and see if it works. It does require a bit of soldering though. There are some threads on here on effecting a repair. I've used standard rechargeable AA's in a cage strapped to the siren on my current car, but Maplins used to sell some similar batteries that would fit.

    Otherwise, Audi will sell you a new alarm unit, but they're circa £230 last time I looked.

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