One electric window not working

[ChrisHC]

I dismantled and cleaned both the electric window switches on my 1987 (pre-facelift) 325i Sport last year and both windows were working perfectly. I got the car out today and found the driver's window was not working at all. As the passenger window works I assume it cannot be a fuse problem. I tried swopping over the switches but the driver's window is still dead. Opening the door makes no difference.

Do I now start investigating the motor or are there any other tests to do?

[biffer]

when i got my car the driver's motor was as dead as a dodo-even after swapping switches/checking wiring etc.-so fault had to be the motor.

car had dealer-fit Electric-Life window-mechs. rather than factory installed,but still had quality Bosch motors that i could take out and strip-down to see if anything was broken.

a look inside the motor showed everything was perfect, so put it back together on off-chance it would resurrect ,and it started working as good as new.

dunno why dismantelling and re-assembling it would wake it up but that's what happened.

[ChrisHC]

I wonder if the C404 connector could be the problem, what is the best way to test that?

[Brianmoooore]

The scissors type factory fitted electric window winders are ultra reliable - much more so than the dealer fitted type, or the pre facelift 'S' shaped mechanism.
On a '87 car, you could have either type, so until the door card is off, you won't know which you have.
The C404 could be at fault, but the window pins are far from the first to fail. Central locking pins fails first, followed by those for the door mirrors, but of course these could have already been attended to.
The next step is to remove the door card, pull apart the window motor plug and socket, and connect a 21W 12 volt bulb to the socket in place of the motor. If this bulb fails to light when the window switch is operated, then the C404 is the next thing to investigate. If it does light, try connecting a 12 volt battery directly to the motor plug and see what happens.

[ChrisHC]

Many thanks as ever Brian, off to the garage now!

[ChrisHC]

Right, it turns out I have the earlier window mechanism. There is power reaching the motor plug, and connecting 12v directly to the motor produces sparks but no movement of the motor, connected either way round, so I deduce the motor is at fault and the next thing is to get it out.

Does the whole regulator mechanism have to come out or is it possible to detach the motor from the mechanism? The wiki does not seem to cover this.

[Brianmoooore]

The motor and gearbox assembly are detachable from the S shaped mechanism, and have individual part numbers.
I once replaced an early type mechanism with the later type, and IIRC, there was no great problem in doing so, OTHER than the glass is a different shape, which will cause problems if yours is the brown tint. In my case, the original glass was green, so replacing it with the later shape was no problem.

[ChrisHC]

That was quite interesting, I found that after undoing the nuts holding the gearbox to the door interior panel, I could undo the two Torx set screws holding the motor to the gearbox and remove the motor without taking out anything else. When I then tested the motor with a 12v battery it span easily in both directions. Without the worm drive of the motor in the gearbox the window glass could be lowered but it was quite stiff. I had used the car a little over the winter but probably not opened the window, so it had been firmly shut for months and I think must have become a bit stuck, so that the motor could not shift it.

There did not seem to be anything to lubricate or clean on the motor, so I just greased the shaft. I also greased the S shaped cable drive, which I could do because the tube has an open slot on the inside, and squirted WD40 on to the glass channels. The glass moved more freely but there was still a screech from the drive in one position. I tried to get in some more grease on to the cable, I think it is improving and hopefully will go on doing so with use.

I will try to remember to leave the windows open a little if I am not using the car again for a while, so that they are not hard against the seals, and I can push down on the glass if needed to get it moving.

[Contours]

I use a Silicone lubricant in the window channels to reduce friction.

[ChrisHC]

Yes, silicone sounds the best stuff to use but I did not have any to hand, I will get some.