E34 Window Limit Switch Doesn't Seem to Do anything

[jbschwartz]

In trying to determine why power window on my 95 525i (rear passenger) was jammed, I discovered that the motor operates whether or not the limit switch is depressed or not. Doesn't sound right to me, and could be the reason why the window was jammed? Any comments?

[George M]

to gain a solid response, I think you will have to provide more information. Jamming could be due to the window going off its track. What limit switch are you referring to...the window switch outside the door?...or the switch inside the door?
If the motor is operating then your window should not be jammed unless your regulator is broken and you don't have engagement.
More info will help provide recommendations. Also pictures help greatly.
George

[jbschwartz]

Sorry for the vague info. Can't tell you the reason for the jammed window. It just wouldn't move from it's closed position. Motor could be heard making a single click, but that's it.

So....I took it all apart. Once the door panel was off, I started by pulling off the motor housing, immediately realizing that that was a mistake. The housing came off, along with the motor shaft, and the brushes pushed in. I realized that I wasn't going to be able to get the motor back together w/o pulling the motor/gearbox assembly off the regulator assembly. So, I drilled the rivets, removed the regulator from the door, removed the motor/gear assemly from the regulator, and was now able to reassemble the motor. Phew!

I still hadn't looked for the reason for the jam. So I started by trying out the motor while it was still separate from the regulator. It seemed to work fine when operating the door up/down switch. I then decided to see how the (inside the door) limit switch affected the operation. The switch had been removed from its mount during dissembly, and was just hanging. I re-tested the motor using the up/down switch. The motor works with the limit switch depressed. The motor also works with the limit switch un-depressed.

Also, there is no sign of wear or damage that I have seen so far.

Photo link attached/included:
http://eschwartz.com/images/525door.jpg



So, knowing just what I know so far...I'd like to resolve the question of why the limit switch doesn't stop the motor. If this is infact a problem, then I can theorize that the window was jammed because it had traveled too far.

Make sense?

[George M]

Well stated. I guess that is a possibility but likely the window is binding in its track and unable to overcome the channel friction partially aggravated by an aging motor that may work fine in a free state but can jam when loaded severely by an unlubricated track. Try traversing the window up and down with the regulator uninstalled to see how the window slides in its track. I would not be overly focused on the limit switch, but perhaps others that have directly experienced your issue will weigh in. If your regulator gear engagement is good...not uncommon for the regulators to strip in these cars...they your window jamming which may be simply another word for the window being static due to too much friction between the window and track relative to the strength of an aging motor. I suggest you lubricate the window track with a silicone based product and reassemble it and give it a try. If that doesn't work...contact Rigmaster and ask Bret if he will sell you a used motor/regulator assembly at a fair cost from a parted E-34. If I recall properly, the motor and regulators for these cars are integrated units and not sold separately...one part no. on the ETK.
HTH,
George

[George M]

sometimes the root cause for what you describe is other than the obvious components. A dirty or high resistance window switch cluster...perhaps one with spilled Coke in it will reduce current to the motor and hence inhibit function. This was true for example with my sunroof. The sunroof motor in my case was not getting full current because the switch was dirty and the roof would not function at times. A simple dismantling/cleaning of the switch resolved the problem. Many before me mistakenly replaced their sunroof motors only to find that it was a dirty switch which can be cleaned...not even necessary to replace the $50 switch. Mine looked perfect inside only the contacts were dirty.
HTH,
George

[jbschwartz]

Thanks for the advice. I'll ignore the limit switch issue for now, and make sure that the window functions in the track.

Stay tuned....

[jbschwartz]

Well, I finally reassembled the motor, gearbox and regulator back into the door. It works fine. I am now realizing that there is a missing piece in the adjustable stop which probably allowed the mechanism to travel too far, causing the jam. The adjustable stop slides up and down in a slot, and is supposed to have a white/beige plastic piece which contacts the rotating gear. One was missing when I disassembled....at least I realize that now.

Off to the dealer...and oh yeah...to the hardware store to buy three bolts to replace the drilled out rivets. The temporary ones I have in there now just won't last.

Jonathan

[George M]

Congrats Jon...can you take a pic of the part you are referring to? Is this part available separately from the dealer or identifiable on the ETK?
Thanks,
George

[jbschwartz]

George,

I pulled the stop assembly and took a picture. Imagine my surprise when I noticed something new.

Note that there is room for two of the white plastic pieces, but only one exists. Now take a look at the shiny damage in the bottom right corner (red highlight square). This must have happened yesterday while operating the window without the second plastic piece. The regulator took a chunk out of it.

Can someone confirm whether or not the second plastic piece is infact missing? I'm headed to the dealer this am to check it out.

[jbschwartz]

The photo might not be visible.

Here's a link:

http://eschwartz.com/images/stop.jpg