Hi, I got a really strange problem with rear right window on my 1987 300TD wagon. Yesterday the window stopped responding to central console switch completely and the switch on the rear door makes window go down, but not up. First I thought it must be a faulty switch, so swapped both, central console and door switches with left ones; still the same problems and left side still works fine with switches from right side.
So I established that switches are fine and went measuring voltages on all terminals of both switches; they are exactly same on left and right side!
I managed to get the window up eventually by switching two wires that go from rear switch to window motor; after doing this window went up (when pressing rear switch down), so actual regulator is fine as well.
Could someone point me to some troubleshooting procedure or maybe a ling to wiring schematics that could help me understand what could be going on...

Mercedes had a rare brain fart in the engineering department on this era car. They picked wire going across the hinge points with a few coarse strands instead of many fine strands.

Over time the wires will fatigue and break across the hinge point.

Remove the door card and b-pillar trim and inspect the wires to the affected door.

BTDT

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Thanks for sugestion; will start with testing resistance on the wires between central switch and door switch.

I have the same issue with the left rear of my sedan. It's the wiring to the door.

Ditto when I had a 1987 300D Turbo. The wires broke, punched through the insulation, and shorted to the chassis. The same problem affected the rear dome and puddle lamps; I had to rebuild both left and right cables where they went through the rubber accordion.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Yes, it was a broken wire in the door jamb; thanks to all for pointing me to this!