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Major electrical problems - help !

campervan Jun 2, 2013

  1. campervan

    campervan New Member

    Having left my 04 A6 2.5 TDI Avant for a few hours I returned to find that the central locking wasnt working. On opening the drivers door with the key there was a strong smell of burning and on removing the fuse box cover I found the cig lighter fuse had melted and there was arching across the remains of the fuse holder (had previously been using a sat nat plugged into the socket). The battery was nearly drained but the car started with most of the dash warning lights on.

    On stopping the car and removing the key the engine kept running !

    I stopped the engine by stalling it and then found it wouldnt restart as it appears that the immobiliser was on. Disconnecting and reconnecting the battery allowed me to start the engine but still had all the faults - and it wouldnt stop again !

    I've previously had problems with water ingress into the passeger footwell which affected the central locking but had replaced the control module and all seemed fine.

    Anyone got any ideas ?

  2. TYphoon GB

    TYphoon GB Active Member

    Need to plug in and daignose Vag Com / VCDS.
    First suggest you disconnect and the charge the battery (do not charge connected Just in case)
    Then a few hours with a multimeter is suggested...find every relay and fuse (there are metal tag fuses as well as the little plug in ones in several places).

    If the front of the fuse panel is burnt...check the rear as well.

    Then connect Vag Com ... doing it before may fry the cable or if its an ebay one your PC.

    Best its just low power issues.
    Medium you fried the main fuses and relays.
    Worst fried the ECU.
    That will Vag Com as no comms or no ECU found.
    Then you will need to replace and recode the pump to the ECU and to the Dash

    Good luck probably just a burnt though wire shorting on something.... pretty tough these recycled panzers.
  3. campervan

    campervan New Member

    Thanks for that. Its with the local garage at the moment and I'll pass this on and let you know how it goes


  4. campervan

    campervan New Member

    So the diagnosis is the wiring loom has been fried.

    The damage starts from the cig lighter socket wiring and goes far into the rest of the loom. Seems that the start of the fault could relate to my use of a sat nav plugged into that socket (?). Why the fuse didnt blow and protect the wiring is unknown.

    Its likely that the car is beyond economical repair - its had to accept this is due to a 20p fuse not operating.

    Might be worth sharing this as many people will be using things plugged into the cig lighter socket.

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