83 240D
And next on my to do list is,,,,, ta da,,,, power windows. So far what I know is (not much) Two windows are inoperative. The front passenger, and the rear drivers side. no motor sounds that I can hear, and the rear window will not work with either switch. I will be into the doors to fix the vacuum elements, anyway, so i was wondering if there is a slick way to eliminate or point the finger at the offending component? It's a long drive to any parts house or boneyard. What say ye all?
Jon j

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Jon J.
81 240D

Check the fuses first, then check the switches. If you have power at the switches then take the switch apart and clean with brake clean which most likely will fix it, unless the window motors are bad which is unlikely.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Just as you described it if the windows are on oposite sides, is a symptom of a bad Fuse or the tips of the Fuse not making good contact.
Mercedes wired the car so that one Fuse controls one Front Window and the Rear Window but on the opposite side.

When this happend to me a visual check of the Fuse looked good. However, when I pulled the Fuse the tip of the Fues was burned off.

The next most frequent cause is the Window Switch Contacts being burned inside of the switch. There is threads in the DIY section on how to clean the Switches.
DIY Repair Links
http://www.peachparts.com/shopforum/forumdisplay.php?f=82
http://www.peachparts.com/Wikka/DoItYourSelf

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84 300D, 82 Volvo 244Gl Diesel

Almost certainly the fuse, they made them in an X pattern so that there would always be ventilation. There is always the chance of the motors siezing up in these old cars too. Here is your course of action, and check out the excellent links above:
1. Fuses
2. Switches
3. Motors. Sometimes moisture can leak in and corrode the gears and motor mechanism. A good cleaning and lube with WD-40 or PB will get them working again (did all 4 in my SD this way)
4. wiring in the doors. The wiring in the "accordian" rubber boot in the doors can get stripped and brittle with age. Before hacking it all up, check for continuity from the switch to the motor using a multimeter.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

I would have never thought that. After all, two windows worked. A fuse would not even been in my sights. I'll look at it in the morning. Thank guys.
And I was going to order a pair of switches. I think I'll hold off on that now
Jon J

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Jon J.
81 240D

X2

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Codifex
1981 240D ChinaBlue (Got her running with a donor engine.)
1983 300DTurbo w/sunroof.
1984 300TD manual sunroof. (Electrical Gremlins)

83 240D

I checked the fuse, there is power to both sides. I did remove them and clean the ends and the holder. Also switched the fuses with each other, no change. I noticed in the fuse box lid there is a relay for the windows. Could this be the gremlin, and if so where is the little bugger hiding?
I have not ruled out power supply, because of the noted symptoms.
Jon J

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Jon J.
81 240D

Check for power at the switch.

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Codifex
1981 240D ChinaBlue (Got her running with a donor engine.)
1983 300DTurbo w/sunroof.
1984 300TD manual sunroof. (Electrical Gremlins)

Where do i test on the switch. I have no idea where the hot wire is as I have never had the switches out. also If I have power to the fuses does that mean the relay is OK?

Jon J

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Jon J.
81 240D

RANT :
I do not understand why MB was not smart enough to put some kind of manual emergency window crank in their cars... they had that feature for the moon roofs....

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

It's difficult to see, but the rocker action pivots the tiny arrows from left to right as a unit connected by the dashed line. I.e. for the underlined RH FRONT to go down, the left-most arrow above #4 pivots to the left of the sausage and stays connected to power and the right arrow above #3 pivots off the sausage and connects to ground; so for down, at the switch 5 is hot "in" 4 is hot "out" and 3 is gnd. Up 5 is hot, 4 is gnd, 3 is hot.

Diagram is for a 300, but I presume the 240 switches function the same.

Attached Files

scan0001.pdf (652.8 KB, 313 views)

I'm finally going to have time to work on this car this weekend. I've made a first things first list due to the number of things that need attention. Probably get to the switches Sunday. I have some vacuum leaks in the doors so I thought while I have them opened up I'll test the motors, and then move on to the switches. I have a pretty good understanding now of how they work thanks to all the response from this forum . Thanks again
Jon J

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Jon J.
81 240D