Crossed window electrics1984 300D Turbo

Some incompetent mechanic has been working on this otherwise pristine car, and I have sorted out many problems already, but this one is driving me nuts. I have all electric windows working now except the
left rear. If I plug in this socket under the rocker switch on the center console, the dash and accessory lights illuminate (headlights off) and the window still doesn't work. I checked the color coded wires on the plugs, and they seem OK (but the codes in the Mercedes Troubleshooting CD don't exactly match all the wire colors on the car). I applied 12V to the motor, and the window works fine. I took apart all the rocker switches, and cleaned them. I must be getting 12V feeding back the wrong way through one of the tiny bulbs in a switch. Must be a pin in the wrong socket. Any tips on where to look next?
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Your investigation doesn't mention the relay. The switch you press powers a relay which supplies the current to the motor. These relays are in 1" x 1" aluminum boxes and are interchangeable so by process of elimination the dead one can be found. Look near the car's fuses.
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Had a similar problem on my wife's '81 300D. Turns out each of the terminal connectors to the switches on the center console are apparently one-on-one with their respective windows. The connector on the right rear on mine has an extra wire which is apparently what allows the driver to control (through the lockout switch) the ability to operate the rear windows. I removed and cleaned both switches for the rear windows and the left rear window worked perfectly from that point on. Don't know if this helps but my left rear window also worked when I plugged it into one of the front two switches but would not work if the right rear switch was unplugged! Again, apparently has something to do with the lockout switch. However, if you have lights coming on with the connector simply plugged in then it would seem someone has tried tapping into a wire somewhere (for new radio, etc.?) or you have a couple of wires worn bare and touching somewhere. Did this problem arise upon return of your car from your "mechanic"?

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Ernie, Your problem was in the switch. I've cleaned all switches, and switched switches, to check that they all work. I've taken apart the female connectors as well, and even tried changing pin connections temporarily, since the colors on the wires don't exactly match the factory repair CD info. But I'm back to this one window and the instrument lights short. I think you're right--someone has fiddled with the radio or A/C and crossed a wire somewhere.
No, my mechanic didn't do this. He is amazing. German-trained master mechanic and master electrician. He learned about brakes in the brake factory, engines in the engine factory, etc. But I use him only for the basics. This is the kind of fiddling problem that takes hours to track down, and it's not a great inconvenience to me that the left rear window won't open.
I bought this car a couple of months ago from a very nice lady who looked after it extremely well, but had some Bercedes-Mends mechanic repair it. You can tell when you see little things broken (like the tabs on the plastic frames around the rear window switches) from not knowing how they come out. I can just picture him saying, after prying something out with a screwdriver, "Ah so that's how they did it!"
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Your probably right about the wire-crossing situation. You might try taking a temporary hot wire and touching each of the terminals in the switch connector. Careful, though, as this could be a bit "adventurous" since you want to make certain you don't hit a ground wire (can be checked first). If you find the respective dash lights coming on when you touch a certain connector then that might help isolate any shorted wires. Good Luck! Tiger might have a better idea so don't hesitate to ask him as well.

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