Window switch
 

My rear driver side window doesn't operate. When the interior lights are on, that switch in the center is the only one not lit up. Also, the rear switch doesn't operate it either. Fuses appear fine. All other windows are functional. Ideas?

You might try contact cleaner on the switches, that worked in my 124, worked on seat switches too. You can get it at radio shack for about $8

All the window switches and the switches at the console that has the rear wiper defroster switch have never worked until I was playing around with one of the rear window switches and all the lights came on! I don't know if it is maybe a grounding problem or what. I have read that it can also be the reostat that controls the brightness of the interior lights, but I think that is if you have no interior lights at all including the instrument cluster lights. My instrument cluster lights have always worked and dimmed as they should.

I do agree with muleears regarding cleaning the contacts. The Germans think you should not be eating and drinking while driving so they put the window switches where they are easily fried by just about any beverage.

As a sidebar, I am jealous of your two W124 OM603's muleears. I bought one with a cracked head last summer and have saved up the money to fix it. I will be ordering the head in the next few weeks. Can't wait to have it on the road. Then it is time to look for one for the wife. I decided she can't have this one because I want the fairly rare leather interior that this one has.

I recently replaced two working window switches that didn't light up, it might not be related.

Once you lift the center console wood panel, it is a simple matter to move switches around, see if another switch will operate the window.

My experience with W123 and W126 window switches is that the contacts soot up due to the design. The switches are not self-cleaning as with sliding contact designs so when they make contact and arc, soot is produced and eventually the soot insulates the contact and the window does not work. You can take the switches apart (be careful not to loose the springs and balls inside) clean the contacts with a pencil eraser and apply dielectric grease to keep it cleaner longer. Eventually you will have to do it again but the process I described will extend the cleaning intervals.

clean them. usually works for mine. most electrical problems I've had ended up being a bad connection or wire or contact.

The center console switch is fine. I swapped them around to check.

The rear door window switch should be fine. I also have a 2nd working switch. Still doesn't work.

Whipped out the voltimeter. Voltages are fine in the center console. But at the rear switch, that's where a problem is. I can't get 12 volts unless I squeeze and/or wiggle that rubber boot between the car and the door. Also looks like voltage is leaking to the other teminals. I tried holding the switch down and manipulating the rubber boot while the switch was plugged in, but still nothing.

Center switch for the window still doesn't light up.

BTW, ended up breaking the tabs and 1 hook on the door handle trying to take off that door panel. It was too late by the time I got to the DIY. Sigh.

I'm pretty frustrated at this point and don't know what to do next. Thanks for letting me vent!

It sounds like you found the problem, a broken wire where it enters the door,