I recently got an '85 300D (267K) and the rear power windows will not go up or down. Doesn't matter if I use the center console switches in front or the windows on each door. What are some possible causes? I don't hear anything like the motors trying to move the windows or anything like that.

vielen danke,
FrankieZ

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FrankieZ
84 500SEL EURO 87K
85 300DT 267K (not my miles tho)

I'm not sure how the circuits are set up. Youreally need the CD for the wirung diagrams. Check to make sure there are no blown fuses. Most likely the motor is burned out. They are not very expensive and the Partsshop carries them. The window motor for my 87 was around $130.

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Deezel
87 300TDT
150,000 miles

I have seen the windows "stick" if not used often, hold master switch down and have someone else "slam" the rear door a couple of times. Are you trying to use the rear switch's? Perhaps you have the "child lock" engaged. It is on the driver's master window switch. Check that first!

OOP'S, Sorry about the master switch comment I did not read your complaint thoroughly. I have also seen wires in the door jam break, but not on both rear doors at the same time. Try opening and closing the doors while depressing the switch. Good Luck, Happy Motoring! Phill

Please clafify if they were inop when you bought the car or if it has developed on both windows at the same time since you took ownership.

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Deezel
87 300TDT
150,000 miles

I would check the ground circuit through the left switch for the rear window cut out function.

This switch keeps the rear windows from working for child safety. If the switch goes bad it can keep the front switches from working also. (I think). Try pushing the lock-out switch in and out a few times.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

I think Steve may be right because I just
replaced the driver side window switch
on my 300D. I tested the old one first
and when I unplugged the center permission
harness, The rear windows did not work.
Also the harness wires were loose because the
bottom clip-on plate of the housing had fallen off.
1.5 cents worth

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1979 300D
133K miles
1989 300SE
1995 C280

Well, fellas. I tried to exercise the child prevention switch and to no avail. So I took off the center console and after disconnecting the connector to the switch, I put my ohmmeter on it and tested the continuity of the switch. It's OK. I assume all the switch does is cutout the voltage to the switches on the door panels. My next step I would like to try is to pull a door panel and make sure I have the voltage to the switches. Are the switches wired before the motors or after the motors? I would assume that they are wired before the motors. But I'm still kinda' scratchin' my head saying "yeah, but BOTH motors aren't workin'?"

How do I pull the door panels so that I can check power to the switches?

Thanks fellas,
FrankieZ

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FrankieZ
84 500SEL EURO 87K
85 300DT 267K (not my miles tho)

I had a 300 SD and my mother in law in the back seat put the window down on a 100F day and it would not go back up after that no matter what.

Power was going to the window assembly, however, something inside of it was shot, and I had to splurge to buy a whole new window motor. It was not cheap and it worked right away after that.

Well, I pulled the drivers side rear door panel and I wedged a little screwdriver into the front console window switch for the window on this door to keep switch "on". I measured voltage to connector but I got no voltage on any pins. What pin numbers or color wires supply power? I'm still finding it hard to believe that both motors went out.

Thanks,
Frank

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FrankieZ
84 500SEL EURO 87K
85 300DT 267K (not my miles tho)

The motor runs off two wires. It works in the other direction if you reverse the polarity, which is what the switch does. Each switch has power and ground going to it and the outputs are power and ground. The outputs are reversed to change direction. This may be called double pole double throw. Internally there are two switches moving.

This needs to be studied on a wiring diagram first. I have fixed hundreds of these and my first step isn't the door panel. It is the wiring diagram.

But, if you are in the door, check power and ground at where the motor wires are screwed to the harness. Check both sides of the circuit!!

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Check the power window relay. Behind the fuse nest under the hood. Controls power for all the windows.

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Jeff L
1987 300e
1989 300e
1987 BMW 325

Steve, I guess you're right-I do need the wiring diagrams to diagnose this malfunction further. I figured as much about the polarity being reversed. I'm kinda' leaning towards having my local MB mechanic check it out, but then I'll miss out on the satisfaction of fixin' it myself!


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FrankieZ
84 500SEL EURO 87K
85 300DT 267K (not my miles tho)

You may take the console switch module out. Disassemble and clean it. Dirt is easy to get in side the switch due to the position of the switch. The front and rear switches within the module are different. Do not try to troubleshoot by switching the two.

David

Well, I just viewed a wiring diagram and I was wrong about the safety switch wiring. Both front switches have their own ground circuits. This almost certainly means you have two separate problems.

It can not be a relay problem or your front windows wouldn't work (BTW the relay is behind the instrument cluster on a 123 body in a metal support that keeps it from being accessed from the bottom).

It cannot be a fuse as the windows are fused LF/RR RF/LR.

I would suspect switches first and stuck motors second. If you feel industrious the motors can be disassembled, cleaned and lubed and often work for years. A professional technician might not offer this service due to the risk of failure. We have done scores of them and see about a 10% failure rate within our one year warrantee period.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician