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A hollow victory - power window fixed

970 views 5 replies 2 participants last post by  augapfel 
#1 ·
Driver's window wasn't working when I bought the car. switch and relay clicked, and there was a thunk noise in the door panel. suspected a weak/dead motor, or broken regulator.
dug into it last night - first thing is I applied 12v directly to the motor via the terminal block on the door (after removing the inner panel). sparking but no movement of the window.
removed the regulator/motor, bench tested and moved very powerfully and quickly in both directions. ??? hmm. No teeth broken on the regulator (didn't remove the motor to check teeth condition there)
I lubed things up (it wasn't totally dry) and reinstalled. window now works powerfully and quickly.
It's a hollow victory because I still don't know why it didn't work before, or why it works now.
One thing I have noticed is that it seems to really crank it up into the door frame hard before cutting out. Maybe it was jammed from being pushed too far up?
 
#2 ·
Don't know what you were hearing but there's no relay involved with window operation on an 88. Not to facilitate up/down action anyway.
Normal front window failure is a stripped regulator rack at the full up position. That motor is powerful and if the operator leans on the switch too long the teeth get stressed until they strip at that end. There's no up stop but there is a plastic collar sandwiched between the motor and the regulator to stop the motor on the way down.
 

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#3 ·
Hmm, that is interesting. I am certain that when I pressed the switch carefully and slowly I heard a click from somewhere under the dash, but I could have been mistaken - perhaps it was the motor trying to move?
Definitely no problem with the regulator rack - I ran it through the full cycle on the bench and checked it over.
aren't these windows 'one-touch' up and down?
because that seems to be the way my switches operate. When I push up the switch locks into place until the window is at the top, then it clicks off. Same with going down - the switch locks into place until the window is all the way down. Or do I just have seriously sticky switches?
 
#4 ·
That's not normal switch operation. The switches should release as soon as you lift your finger.
Does just the driver's door do it? That one, of course, gets the most use and gets funky first. If all the switches are screwy like that someone spilled a grande moche latte on the console and the switches are now gummed up.

And the only relay in the system is the one that activates the PW circuits at engine startup. That relay is located in the underhood fuse box.
 
#5 ·
Aw, man! :crybaby2:And here I was impressed with the MB engineers incorporating a one touch up/down function. Oh disillusionment! I guess I'll get into cleaning out that half caf decaf espresso latte mucho grande from the switches this evening. maybe that will get the driver side rear window working (the only one that remains non-functioning)

Thanks very much for the info :thumbsup:
 
#6 ·
With age/high miles the power window wires that pass from the b-pillar into the rear doors crack and separate. One of my 88s has already had this repaired. The other TE is now showing intermittent left rear window operation. I guess I'll be fixing that one soon.
The rear window regulators on these cars are problematic. I had to replace both rears in my sedan because the windows were inop. The regulators were not worn out; in fact they were barely used. New regulators (not cheap) lasted about 5 years before they started to act up. I won't fix them again. Running the glass all the way up seems to jam the mechanism so try to avoid that.
 
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