No windows working 83 300D - PeachParts Mercedes-Benz Forum

Rudebutler · #1 06-12-2007, 04:25 PM

Yesterday all of the windows in my 83 300D died. I have changed the fuses in clips "a" and "b." I also replaced the switches.

When I start the car and have a rocker switch depressed, I get no voltage at the fuse box.

As I look at the wiring schematic, it shows power going to 2 window lift relays before the fuse box. Where are they? Could they be the culprit? Where do the grounds connect? What would make me lose all 4 at once?

Everything else in the car is working properly.

Wiring is not my strong suit. Any help is greatly appreciated!
Rich

Knightrider966 · #2 06-12-2007, 04:41 PM

If your car is anything like mine the relays are under the panel where your window switches are. I had this problem and one of the plugs under there came loose and I plugged it back in and viola! No problem! Lift your switches out, unplug the wiring harness from each one, then remove your ashtray and ashtray mount assembly and then push your woodgrain panel back toward the rear seat and lift up. You will see a bunch of relays under there!

#3 06-12-2007, 04:42 PM

Just for fun, try replacing fuse #8, I believe it provides power to the relay.

Rudebutler · #4 06-12-2007, 10:24 PM

Craig and Knightrider-thank you for your help!

Replacing fuse #8 did not improve the situation.

The only relay under the shift cover is for the emergency flasher. There appears to be a relay-shaped box behind the radio, so I have begun to remove the entire center console cover so i can get at it.

Anyone know what these relays look like? How many pins do they have?

Once I get the center console out, I can trace the lines individually

.

Any other suggestions? The A/C needs to be recharged and it gets awfully hot with just the sunroof open!

KAdams4458 · #5 06-12-2007, 10:40 PM

I can't offer any suggestions, but I'm curious where you found a wiring diagram. I need one to diagnose the windows in my '77 300D, and have not found one yet. An '83 diagram is likely similar enough to get me through the repairs.

burntcloth · #6 06-12-2007, 10:56 PM

Wiring diagrams should be in the service manual.
Do you have a service manual?
If not, they're $20 for a CDROM from MB Classics.

#7 06-12-2007, 11:11 PM

The W123 diesel Haynes manual also includes decent wiring diagrams.

KAdams4458 · #8 06-13-2007, 02:12 AM

I don't have the MB Classics manual, just a number of PDF files from it, none of which include wiring, unfortunately. If it's in there, I'll order a copy. I did look at the Haynes manual, and it has wiring for the chassis, but not for the power windows. I might have missed it, but I didn't see it there, and so chose not to purchase it. The Chiltons manual is even more useless than the Haynes.

The only problem I see is that by the time I can get a disc from MB Classics, I'll have figured the wiring out on my own. I've just been hoping to save some time, since working on the car involves driving an hour and a half away from home, and I can't get out there very often. I try to make the most of my time researching before I head out to work on the thing.

toomany MBZ · #9 06-13-2007, 03:45 AM

I have a Haynes, and a CD-ROM, I cannot read an electrical schematic, sorry. Wouldn't know a relay on paper, or CD.

Rudebutler · #10 06-13-2007, 08:41 AM

K Adams-

I'm working from the diagram in the Haynes. They have specific diagrams for each chassis run, so there will be a specific diagram for your '77.

They're not easy to read, but if you trace the circuit you need with colored pencil it makes it a little easier to follow.

Anybody out there have any other hints? I really suck at electrical

KAdams4458 · #11 06-13-2007, 01:23 PM

Well, then maybe I missed that diagram. Eh, I'll go look at the Haynes manual again. Once I have a diagram to look at, I might be of some help.

Rudebutler · #12 06-14-2007, 07:10 PM

OK-I'm getting close! Fuses a and b aren't getting power. I jumped a wire to that circuit and all the windows worked just fine. There is a red wire with a blue stripe that comes off the back of the fuse box for those circuits. I checked and there is continuity from an inch down the wire to the front of the fuse box, so I don't think it's the connection to the fuse box. What I can't figure out is where the red/blue stripe wire is supposed to get it's power from. Anyone know where the other end of this wire connects?

I did find a similar wire coming out of this weird pink and turquoise egg-shaped thing behing the dash. There are others like it. What are they, what do they do, and why did the Easter Bunny leave them in my Benz?

#13 06-14-2007, 09:52 PM

According to my wiring diagram, the red/blue wire comes directly from the window relay. I don't know where it's located, someone here should know.

Rudebutler · #14 06-15-2007, 07:17 AM

Hi Craig-

That's where I'm getting confused. Unless I have the wrong relays, they are above the driver's side wheel and there are no wires that match the red/blue stripe wire that comes off the fuse box. I've been trying to follow the wire from the fuse box, but it enters a thick bundle that I can't get to under the dash. It's all wrapped in that hideous sticky black tape.

#15 06-15-2007, 08:18 AM

Quote:

Originally Posted by Rudebutler

Hi Craig-

That's where I'm getting confused. Unless I have the wrong relays, they are above the driver's side wheel and there are no wires that match the red/blue stripe wire that comes off the fuse box. I've been trying to follow the wire from the fuse box, but it enters a thick bundle that I can't get to under the dash. It's all wrapped in that hideous sticky black tape.

I do not think the window relay is in that relay box.

Anyone, where is the window relay on a W123 300D?