Something strange happened today. I got in, started up, rolled the windows down, drove around for a while, just like usual... rolled them up for a rain shower, rolled them back down.... or tried to. All four windows were randomly dead.

Funny thing is, the auxiliary circuit that allows the windows to function with a door open but the switch off... works perfectly. All four windows working on that circuit. However, with the doors closed, all four windows are now stone dead.

Can't find any other electrical problems to speak of. Fuse box looks okay.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

I see you've passed the quarter million mile mark... awhile ago...

'Just guessing:
1.Electrical portion of the ignition switch(Plugs in ...in back of tumbler part)
2.FUSE (?) It's always a fuse [That should be #1]
3.Wiring.

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'84 300SD sold
124.128

Although fuses appear to be digital (either 1 or 0), they are in fact analog, not by any one's intention, but due to the innate perversity of nature. The ends of the fuses have a tendency to corrode or oxidize; this reduces their ability to conduct the large numbers of electrons required to make the window motors operate. The window circuits use several fuses and it's not always obvious which one is at fault, especially if they appear good to the eye and to the voltmeter. Therefore, I would first check and clean or replace all of the fuses. If they are aluminum, replace them with copper.

Once you are certain that the fuses are good, you can move on to tracing the circuit that goes through the key switch and the associated relay that energizes all of the window circuits.

Since all four windows are involved, it's probably not the through-door wiring or the console switches, which we would otherwise suspect after fuses.

Your "operate windows with door open but key off" feature must be unique to the SD/SDL models; my '87 300D has that feature for the power seats but not for the windows, alas.

Let us know what you find.

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

Problem was cured by hammering on all the relays in the fuse panel with my pocket knife handle.

Now, which relay was it?

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

I don't see anything in the schematics that allows the windows to operate independent of the keyswitch when the door is open..........in similar manner to the seats.

The relay for the windows is in the first row as you face the box from the left side of the vehicle.

It's the second relay from the left side (the side with the fuses).

It was the one that you "fixed" with your pocket knife.

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daw_two
Germantown, TN

Links:
Sold last car --- 05/2012 1984 300D Light Ivory, Red interior
Cluster Needles Paint
New Old Stock (NOS) parts

Past:
3/2008 1986 300SDL "Coda"
04/2010 1965 190D(c) "Ben"
& many more

Nonetheless, mine have done that flawlessly since I bought the car. I assumed it was a feature for when you get out, take your keys out, shut her down, and then realize your windows are down and you don't want to get broken into.

Does yours not do this?

I'm not arguing with you, I'm just confused. I thought it was supposed to do that.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

I'll have to try it. I cannot find any door switches in the schematics for the window circuits...........so...........I'm confused as well.

Well, it's entirely possible that my car is wired wrong somewhere... in fact that's more a probability than it is an improbability. it has just been so useful that I assumed it was a feature. I'd check my CD FSM for the schematics except it is at home and I am at college - next time you're in yours, check it just to see if I'm miswired.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

Quoting this from another thread on similar issues. Here's another vehicle doing precisely the same thing as mine, FWIW.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

Open the glovebox, check the owner's manual. If it's supposed to do it, it'll be in the owner's manual as the key-window feature was in the '90s 124s.

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Gone to the dark side

- Jeff

My driver's side rear door window is not working. It is up, and won't go down, with either the console switch or the switch on the door. All others work just fine.

707 it sure is nice to know what year, model, and even brand of car you're discussing.

On some models the wiring to the door can fail from flexing, try holding the button down as you open the door to see if it moves.

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Gone to the dark side

- Jeff

The above in red happens.
I do not know if he has the same style fuses or fuse box but this is what I found when 2 of my windows stopped working. The fuse looked good at first insection.

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84 300D, 82 Volvo 244Gl Diesel

I'm experiencing the same problem intermittently. All windows will operate fine, then I stop and none will move up or down. 10 miles down the road, I try again and they are good. This has happened three times in as many weeks.

First time it happened, I replaced both fuses and the windows were still inoperable. Ten minutes later, I found my multimeter. Started the car again and the windows worked.

All I can think is the keyswitch I replaced a couple years ago is getting flakey.

Car is 1983 300SD

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Greg Schwall

1983 300SD - 465,000 miles