Rear electric window motor issues

[pmansson]

The rear left window stops half way, with the motor continuing to run. If I pull or push the glass it will continue to move with engine power. It just needs some assistance at 1-3 places along the way.
What is the problem, please?

 

[MMercury]

The rear left window stops half way, with the motor continuing to run. If I pull or push the glass it will continue to move with engine power. It just needs some assistance at 1-3 places along the way.
What is the problem, please?

The answer to your problem is probably simple but dirty. I doubt there is a problem with the motor or its contacts. The first suspect is congealed grease restricting the movement of the window and/or the window regulator. If you remove the access plug that reveals a white gear, you can manipulate the gear to move the window up or down. When you realize how much resistance there is, you can appreciate how hard the motor works to drive the apparatus. When things were new and clean things worked more smoothly.

It is a bit of a pain to access the regulator and motor, but if you remove the panel with armrest it is not that difficult. Just degrease, clean and regrease (I used white lithium) and you should be good to go. That being said, I have also found my own motors gummed up and found it not that difficult to free them up by scooping off the older grease and replacing with a fresher supply.

It is also possible that the switches controlling the window motor are gritted. Frankly, the switches are not the greatest design as evidenced by BMW's decision to use different switches in the later models. I have discovered that they can benefit from cleaning because the contacts are rarely pristine.

hth