Hi All,
The drivers window on my 1999 XK8 convertible has suddenly developed an unusual problem. When I put the window up it reaches its maximum travel but if I keep the switch pressed the window motor keeps turning. Obviously the window can only go so far and when it cant go any further the cog on the motor spindle jumps off the window frame making a hell of a noise. So far I have tried the following to no avail. Replacement switch, motor and complete door latch mechanism. Car has a new battery. I cant work out what makes the window stop when it reaches its limit? It operates normally when closing.
Thanks.

 

I don't know what's wrong, but just a factoid or two to maybe help your investigation ...

What makes the window stop? Two parts: what stops the window, and what stops the motor. When the window comes up against something mechanical that the motor can't push it past, it stops (duh). But the motor may not know about this (see below) and so may keep running ... there are no position sensors telling the motor "we're done".

So the motor stalls, or there's a clutch (I forget which) but either way the motor is still powered. After a short interval, a second or two, a logic circuit detects that we're no longer moving, shuts off the motor and "remembers" the position of the window for next time, so it can shut down the motor when it gets there without having to "learn" again where to stop pushing.

(Having learned where the upper limit is, the system can do the little trick of lowering the window just a bit when you open a door or operate the top, and then putting it back where it was afterward.)

Good luck.

 

Thanks for the help Dennis. do you know if the logic circuit is part of the motor or is it elsewhere?

 

According to the book, the windows are controlled by the DDCM or the PDCM. See attached.

Chris. T.

 

Chris,
Many thanks for the attachments. Give me some more options to check out.
cheers

 

Thanks for the help guys. I still cant find the problem. I think its a mechanical issue rather than an electric one. Can anyone direct me to a site where I can find out how to remove the window glass and the regulator. Ive stripped the door down but cant work out how the window separates from the regulator.
Cheers all.

 

Here's the relevant sections from JTIS.

Graham

 

Bigkriss,

Here are good links for you: https://www.jaguarforums.com/forum/x...ighlight=glass

I don't remember having to remove the glass to pull / replace the reglator. You will have to secure the window in up position to get it out of the way once you disconnect the regulator arm (see link for that part). I used a Stanley Pipe Clamp to do that. Takes minimal pressure to hold in place as long as you still have your little rubber pads on your pipe clamp.

Replacing the regulator turned out to be a much easier job than I anticipated.

Ask us if you have more questions.

John

 

Window problem sorted Thanks all. Broken teeth on quadrant on regulator. Got a brand new one with motor for a great price. Links to photos really useful. Cheers all.