Hey guys,

89 S4 that had intermittent drivers side window operation. Sometimes it would work & others it wouldn’t. It eventually stopped altogether so I figured the motor had gone. Purchased a new/used one from 928s Intl. put it in and window still won’t work. I put a different switch on to rule that out. Any suggestions?

 

Ash,

I have had a similar problem for as long as I can remember. In the end I figured it was all to do with resistance to motion and the motor stops when it meets a certain degree of resistance- too much resistance and it does not work at all. Time after time I remove the door card, pull the motor from the lifting arm, test the motor - it works and then put it back and the system works. I usually give the lifting quadrant a bit of a lube and avoid grease on the lift slide or whatever that bar like thing is called as the grease tends to dry out and then create more resistance to movement.

The thing then runs for a couple of years or so and then the problem starts again as was the case recently. Too damned hot at the moment to do anything I do not have to do and with 40C ambient temps I do not feel inclined to run around with the windows open anyway.

I rather suspect this is a very common problem.

 

It could be the nylon button that moves in an arc round the regulator. Corrosion builds up under the button and around the spring washer there, and causes too much friction between button and track. You just need to pry the button out and use emery paper to clean the washer and the recess. This for require removing the complete regulator from the door, not just the motor. I may have some photos from when I was refurbing the window lifter on one side.

 

Go to this thread for how to service the motor - if you didn't check out the one you bought from 928 Int. See my post at the end for easy way to remove the motor from (and re-install it) the transmission: .https://rennlist.com/forums/928-foru...ow-motors.html

Also be sure you have power at the connector to the motor when you push the switch for both up and down. If you do not, then it's a wiring problem. The wiring gets bent every time the door is opened and closed. Metal fatigue could be a problem as well.

Gary

 

My 84 just started having an intermittent issue and turns out it's the wiring or the ground. If I open and position the door in just the right place it works. It sometimes works with the door closed too. While parked and operating the switch, change the angle of the door slowly and see if at some point window motion is restored. If so, the motor is likely fine and you can explore the wiring fault.

Haven't had a chance to look at mine as I've been repairing my 911 with failed supercharger pulley that metled the plastic idler pulley next to it
This is what I did yesterday - fun

 

Thanks guys