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Door / lights - Microswitch or Module?

SixDegrees Dec 9, 2009

  1. SixDegrees

    SixDegrees Member

    Ok, so back to the old door switch / interior light issue. Read a few threads which all point to the Microswitch being at fault and a good dose of WD40 should sort it.

    So, I did that based on the fact that the dash was displaying the door open symbol when in fact it was shut and the interior light was on permanently.

    The issue has changed in that the door open symbol (dash) is no longer showing and the interior light pulses evey second or so with a click from the dash... which is also setting off the alarm!

    So, with the new problem in mind I've followed advice and links in the threads which pointed to cracked solder on circuitry - admitedly this was for a MK4 VW but I was taken there via a link from this site.

    Anyway, upon investigation the door mech in my 2001 A3 is nothing like that of a MK4 and so the cracked solder issue seems like a red-herring. However inside the door there is a black module with 3 inputs located just below the window-line about 1.5" x 1.5" and sealed, plus the mechancical door gubbins with the micrtoswitch.

    So, any pointers to to which I should be replacing given that the visual symptoms have changed from being a static linterior light and open-door symbol on the dash to a pulsing interior light, no symbol on dash and the alarm going off (cos it thinks the door is open).

    Module or Mircoswitch? Admitedly, I don't know if this wee black module has any bearing on the issue but its the ONLY other thing inside the door that appears to be electronic and poss related to the the door / window operation.


    Last edited: Dec 9, 2009
  2. Westy

    Westy Well-Known Member

    I'm guessing you saw some of my old posts on this issue then! I had an absolute nightmare with mine and it turned out to be a wire that was shorting to earth and making the ecu think the doors were open.

    Anyway I doubt my issue will ever be seen again on these boards as my wiring didn't even match the audi wiring diagram!

    From my experience of stripping the locks and door cards over the last few months I will say that the things to check are door card connectors and micro switches first.

    I was getting different dis results depending on whether I had the door cards plugged in or not as the wiring from the alrm module in the boot runs down the passenger side, through the door card then behind the dash to the dis.

    You may also notice that the passenger side has 2 micro switches where the drivers side only has one. This is because the 2nd microswitch is for cars with rear doors. On a 3 door car the 2 micro switches both come together on the wiring diagram but if one of them is nackered it will cause problems.

    It will be a lot easier to diagnose if you have vagcom
  3. The Doctor

    The Doctor Well-Known Member

    I gave up & got mine replaced. Just got really annoying to see the "door open" display when it was shut & to have to keep the interior lights switched off.
  4. 666markyboy

    666markyboy Well-Known Member

    i would have thought if when you sprayed the microswitch with wd40 and things changed then that would at least say that your in the right location
  5. Ecto90

    Ecto90 New Member

    hey I have no interior lights come on only when driver door opens and window doesnt reset when the door closes. passenger works fine. think WD40 in door lock mech would help?

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