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1999 A6 tdi central locking with a mind of its own.....HELP!!

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by alibob, Dec 17, 2009.

  1. alibob
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    alibob Liskeard Classic Cars

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    [Dec 17, 2009]
    Hello Chaps.....Its been a while (Shows how reliable the old girl has been!) but recently while driving along, the central locking has been trying to operate itself. I don't think it is a problem when it is in the locked position.
    I noticed a few weeks ago that the boot light doesn't always come on first time as well and wondered if they were connected problems.
    Also the "shut the windows from the remote fob when you lock it" function has packed up.
    So:
    1). Does anyone know where the switch for the boot light is?
    2). Has anyone had this problem before?

    I am starting a new job soon and need to leave the car in a public car park so any help will be greatly appreciated.
    Al
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  3. alibob
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    alibob Liskeard Classic Cars

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    [Dec 18, 2009]
    Right....I read as many threads as I could on the subject and got the ecu out from under the carpet. It was a bit damp but not excessive. Cleaned all the terminals with switch cleaner and gave everything a coating of WD40 before I put it back together.
    So far it hasn't done it when driving but if I remotely open the drivers door.......All the bloody windows open.

    I am off to Plymouth tomorrow for the first day of my new job and the forecast is for -5 all day so lets hope they stay shut!

    I expect this with my Alfa not an Audi

    Wierd actually....The Alfa shags suspension bushes for a pastime, eats MAFs like they were some sort of engine supplement and depending on its mood, will light up dashboard warning symbols in some homage to Dhiwalhi and then go as black as Maggies heart......And I forgive it and spend my (well yours actually) hard earned cash fixing it,

    The A6 has one fault in 3 years and I am really teed off.
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  4. olivarley
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    olivarley New Member

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    [Dec 20, 2009]
    Hi Mate,

    I know this isn't gonna help you, but I have the same problem. My car will put its windows down by itself when i open it. When I am driving it the locks, go crazy and keep unlocking even if they are open and the interior light flicks on and dims away.

    I am looking for answers and have too been through as many posts on the subject as possible.

    I am now thinking that it has something to do with the electronic's in the drivers door relating to the locking mechanism. I have been told that there is a common fault with this unit.

    Hopefully someone is going to reply to yours or my posts with a definitive answer on the subject as soon as possible. I too am worried about leaving the car in a public place, in case it opens itself....

    I will let you know if I get any answers or solutions.
    #3
  5. etronic
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    etronic TDI VCDS Map User

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    [Dec 21, 2009]
    You're going in good direction. The switches in circuit attached to locking unit are mostly the problem. That's why it's playing up while you drive.
    #4
  6. alibob
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    alibob Liskeard Classic Cars

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    [Dec 21, 2009]
    forget everything I said...it is still doing it but since I put some WD on the door key and fiddled about with it a few times, locking and unlocking manually, it is a lot better. the good thing is that once I have got home, shut all the windows and remotely locked the car, it appears to behave itself until the morning.
    I was getting fed up with the neighbours knocking to tell me that I had left all my windows open.
    I will try and investigate further on tuesday/wednesday and let you know how I get on.
    #5
  7. AUDIQS
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    AUDIQS New Member

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    [Dec 21, 2009]
    Hi the fault is in the c/locking units on 1 or 2 or 3 or even 4 or 5 in very worst case on each unit there is a micro switch at the bottom .
    What has happened is the rubber seal has perrished and water has gone inside and corroded the switch itself and because its corroded its shorting out causing doors to either to lock/unlock it can hold one of the cycles and your windows will go down or up this mode is sunshine mode.
    THE FIX it to replace the whole unit at a pice of £129 audi sell them or if you are very lucky scrap dealer OR what i did was went through all the micro switches in RS to find the right one i will find the part number and put it in next post there is a a slight mod to do but nothing bit just need 2.5mm drill bit and small selftaping screws job done.
    FOR the mean time look to find which step well light does not light up when door is open and thats the one at fault please check the bulb is ok first, then take door panel off thats 2 screw either end of panel then lift up move to one side look at bottom of the lock and you will see the red and blue wires join them together the will tell the car the door is shut if you want to check first that the switch is broken take the lock mech out and have a look before you cut and join . This may help untill you get you replacement part.
    Soon as find part number will post soon.
    #6
  8. DGSdale
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    DGSdale Member

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    [Dec 21, 2009]
    I'd largely agree with AUDIQS but would suggest that the microswitch is not necessarily corroded - mine was just stuck. I posted this in January this year:

    One thing I didn't mention in that post was that the alarm was costantly going off too - until I pulled the wire off the siren, but once that microswitch was sorted everything was working again, & as I said, cost nothing.
    I'm fairly sure this problem is more common in cold weather because there is a small quantity of grease on the plunger inside the microswitch & in cold weather it goes almost gel like & can cause the plunger to stick & cause a number of different problems. Worth checking out before shelling out.
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  9. alibob
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    alibob Liskeard Classic Cars

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    [Dec 21, 2009]
    AUDIQS.....I have checked the puddle lights and they all come on. However the boot light is very temepremental....Would this still effect the comfort windows and self-locking/unlocking? If it does, is the microswitch in the line or on the boot catch and do you know what operates the boot light anyway? I presume it isn't the 2 switch looking things (like old-fashioned door switch/courtesy light switches 'a la' Anglia/mini/mg) on the 2 ends of the boot (or is it?)
    Interestingly, once the car is shut for the night, it behaves itself.
    I await your replies and thanks to all for the help so far.
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  10. DGSdale
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    DGSdale Member

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    [Dec 22, 2009]
    There is a microswitch clipped to the boot latch mechanism in the same way as with all the door latch mechs. It has blue & red wires running from it. These microswitches tell the central locking module whether or not the door or boot is shut (& they're really quite sensitive). If there is a problem with the microswitch it can confuse the C/L module; e.g. you're trying to lock the car when its being told something is still open & then a number of things go pear shaped! Also, in the case of the bootlid or tailgate, there are a couple of different lock positions for it to be included in the C/L system or permanently locked, needing the key to unlock it (can't remember them exactly)- check out the Audi owner's handbook.
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  11. alibob
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    alibob Liskeard Classic Cars

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    [Dec 29, 2009]
    This is now giving me the right hump....All my puddle lights work. I have tried to isolate each door and the boot individually and it makes no difference. I have already mentioned that I cleaned and dried and treated the ECU in the passengers footwell and can only conclude that it is a direct short somewhere beteween the ecu and the boot.
    Bumps don't seem to trigger it and although I though this problem started when we had the first cold snap, today was relatively warm and yet the locking went totally ape all the way to Plymouth and back again.
    Mind you it was raining quite heavily.
    Any other ideas guys?
    #10

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