Originally Posted by ajme

I have a 1989 190e, different, but related, so my experience may be relevant. The window wires break inside the pillar betwen the front and rear doors, just before they enter the rubber tube to the door. I don't know why. You would not think that there would be much flexing. Both sides had the same problem.

You can check for continuity between the front console switch and the rear door plug, if you have a wiring diagram. On the 190e, the wires have the same colour code at each end, so it is easy. Probably yours is the same. One is always hot (brown) as long as the front console switch is plugged in.