Rear window won't close
 

Though I have managed to get it up now, there's something very wrong.

Driving along hear a "funny noise" from the nearside behind me, thought it might be the nearside rear window a bit open so I tried to close it. Nothing happened, so I tried opening it a bit.
Upshot was, it kept opening more and more but wouldn't close, combined with some disturbing noises.

Eventually found a safe place to park and managed to force it up using hands on the glass and operating the switch. Kept hearing graunching noises as if something (glass maybe ) was caught in the mechanism.
Only got it up in tiny steps, the auto-reverse mechanism kept kicking in. Where are the sensors for that, it might give me a clue?

Any thoughts anyone, I guess the door will need to be stripped to investigate but how difficult is that?

I need to use the car again today so won't be investigating until later in the week. Might scupper plans to go to Audis In The Park on Sunday.

That sounds exactly like my rear door when I went to the Annual Meet!
I only managed to get the window partly closed. So I taped the opening in case of rain.
Stripping the door isn't very difficult. But the wire going to the lock was difficult to fit again, in my case.

In my case it was the wire that had broken off.
http://forum.a8parts.co.uk/showthread.php?t=14232

Johannes I think mine is subtly different. There is motor drive both up and down and the window WILL close, but when it starts moving up the anti-trap mechanism starts lowering it again.

It's quite likely that something is broken or adrift (or debris from somewhere) but I suspect that is fouling the mechanism causing it to reverse automatically.

Thanks for the link to your thread, a useful reminder of how to start taking it apart. I've done front doors, so hopefully the rear is easier.

Andrew, instructions on how to remove the rear door cards can be found here:

http://forum.a8parts.co.uk/showthrea...5205#post85205

My A6 passenger window does exactly the same. I think the cable is frayed so its happy to go one way but not the other. It usually has to go all the way down before it can be persuaded to go up again.

Thanks Sean and MJ, I may investigate tomorrow.
As the motor drives it both ways I'll probably try some silicone lubricant in the glass channels first.

Can anyone comment on my question re the safety back-off which it is doing? Where are the sensors for this?

Its in the motor - it detects the current load and if its too high it reverses.

Thanks. So that's why I can inch it up in small stages while applying upward pressure on the glass. +++

Finding the cause of the obstruction will be the task, unless it's an actual faulty motor.
Given the unpleasant noises I've heard it does sound like a mechanical obstruction somewhere.

Edit: MJ beat me to it!

I suspect there are no sensors as such. I can't be certain, because I've no knowledge of how the D2 electric windows work. But, from an electronics design point of view, the most common method is to use current sensing to detect an obstruction. Current sensing may also explain the need for the controllers to 're-learn' (by holding the switch to fully open/close the windows) whenever the battery has been disconnected.

I've not had a D2 window mechanism fail on me (yet) but it would appear they operate in pretty much the same way as my old Citroen XM windows used to do (essentially a steel wire rope and pulleys) and on the XM they would fail alarmingly frequently. Audi window mechanisms are clearly better designed/built, since they last longer, but ultimately they will no doubt be prone to the same type of failure ... a rusty rope. My guess, I'm afraid to say, would be that it's not an 'obstruction' but a frayed rope. My XM windows often behaved the same way, shortly before the rope snapped or jammed. :(