What's the odds of a switch problem if both windows fail to function........at the same time?

I would not bet on a switch problem. Just want to see if power is getting to the switches, since that is an easy place to check.

And. if the motor and the wiring between the switch and the motor is okay, it would be possible to jumper power to the switch connector and get the window up.

Gotcha.........yep.........no power to both switches is my guess.

I pulled the switch blocks from the console and I do have power to both the LF switch (on pins 1,3, and 2) at neutral position and the RR switch (on pins 1, 3, and 2) in neutral position. Does anyone know where I can get a electrical schematic for the power window circuit on line? I think if I had a schematic, I could isolate the problem.

Thanks

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1985 300D Turbo California Model (134K)

On the front switch, the window should go up if you jumper (at the connector) 1 to 4 and 2 to 3. (Down should be 1 to 3 and 2 to 4.)

Tango,

I don't have a pin 4 on the Left Front window. I have the following colored wires going to these pins:
Pin 1-Green
Pin 3-Red
Pin 2-Black
Pin 6-Blue
I believe I reading the pin number markings correctly.

It still seems odd that both windows on the same circuit would fail simulataneously

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1985 300D Turbo California Model (134K)

That all sounds right, except that you should have a Brown wire at 4 and 5. 4 is ground for the LF window, 5 is ground for the rear window safety switch.

While we are at it, 3 is supply from fuse B, 1 and 2 supply voltage or ground from the switch to motor, depending on switch position. 6 is power for the switch light (LED.)

We are talking about the left front window, correct (the driver's window switch)?

There is no brown wire or Pin 4 on my 1985 300D Cali model. I do appreciate your help. This troubleshooting is not very efficient without a electrical schematic that I can look at so I think I'll wait until my Mercedes mechanic buddy gets back into town tomorrow evening. He has a complete set of factory manuals.
Thanks Again!

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1985 300D Turbo California Model (134K)

Can you verify that you have replaced, not just checked, the "b" fuse. I just had to replace mine, it apparently burned out when I tried to open a frozen shut window. It looked fine, but it had failed. Diagonal window failures are almost always the fuse.

I had a radio and some other problem a while back. Turns out my fuses were just fine .... or so I thought. They were basically all pitted. I was at a repair place one day, the guy told me to replace them right away. A pitted fuse builds up more resistance, and can cause other, bigger electrical problems.

Do yourself a favor. Replace ALL of your fuses with the better, copper fuses. An entire set is like, $9. Buy two so you'll have spares. And if it's not the fuses, then try replacing the switch itself.

jeff 1991 300d, 102k

I have the wiring diagram for your car, but I can't post it because is too big, and if I resize it, you can't read the text. Let me know your e-mail, I will send it to you.

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TangoFox and Brian C. and the others:

You guys were right! The window problem was caused by a fuse that was missing just enough metal to show voltage, but not enough to pass current to the windows.

Thanks Again for all your great help on this forum!

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1985 300D Turbo California Model (134K)

I think that's great advice. The aluminum fuses are the source of much trouble. I bought a set of the copper/brass fuses on Ebay a few months ago. One set is enough, as there were plenty of extra fuses for spares.

Good advice on the fuse replacement with copper/brass. Is there any particular supplier or source for locating these improved fuses.

Thanks, Mark from Arizona

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1985 300D Turbo California Model (134K)

Ebay is the least expensive. Do a search for "Mercedes Fuse" and you will find a number of options. Otherwise, http://**************.com/node/48 sells them.