'89 200Q stuck rear power windows.

[Brett Dikeman]

On Apr 30, 2006, at 9:27 PM, LL - NY wrote:

> Trying to diagnose WHY my rear windows won't work on an '89 200Q. I AM
> getting power to the rear window switches. Safety switch seems to be
> working properly, the rear window switches light turns on and off in
> conjunction with the safety switch. Depressing a switch in either
> direction does cause the dome lights to dim. (One thing of note is the
> rear ciggy lighter doesn't work, and from the wiring diagram, they
> seem to be linked in a series.) I checked voltage at the switch and it
> appears that all is in order.
>
> Has anyone ever had a window that just got physically stuck and it
> simply needed a boost (while the electricals were working "properly"?
> I haven't tried directly jumpering the motor wires (just to verify,
> which two are they?) to a 12V source, it was getting late. Any
> suggestions?

I had a similar problem with my 200q20v when I put it back on the  
road after 6-9 months of not driving it; the switches clearly worked,  
as pressing any of them in any direction caused a big current draw.   
I finally got around to fixing it recently.  Loosening the screws  
that hold the motor case on, I could feel it twitch a bit when I  
cycled power, but nothing more.  I ripped it apart and found one of  
the commutator contacts has a nice big discolored spot on it, the  
sintered bearing had rusted up a fair bit, etc.  Lots of life left on  
the brushes, however.

I removed the regulator gearbox+motor (zip tied the spool to keep it  
intact) and went to town cleaning it up.  A cordless drill is perfect  
for "turning" the rotor to polish the shaft and commutator; a long q- 
tip on a dremel works well at cleaning up rust on the sintered  
bearing.  I use 3M marine metal restorer; it has some sort of acid  
and an aggressive compound that puts an almost mirror-finish on stuff  
effortlessly.  I used 500 or 600 grit paper to even out the  
commutator contacts, cleaned the built-up carbon from between the  
channels with a razor blade, etc...re-greased the gearbox with M1  
synthetic bearing grease, etc. I also stuffed a fair bit of grease  
into the bearing area in the motor case, applied a bit of Boeshield  
to the magnets+rotor etc to keep them from rusting up, and so on.

Works wonderfully.

Oh- the tricky part is getting the brush assembly out, especially if  
the case has corroded somewhat.  If it won't come out easily, apply  
some PB blaster liberally and come back in an hour and try again.  If  
you tug on the white part too hard, you risk ripping various bits off  
the -black- half underneath.  I did a little damage since I rushed  
it, and had to carefully push some wires back into place and re- 
solder connections.

As a physics teacher, you'll appreciate the best method of getting  
the internals out once PB blaster has been applied- tap the motor  
case's tab against somehting like a bench vise.  Viola, everything  
inside slowly pops out.  Just watch that you don't mangle the brushes  
too badly.

Brett