For the first time in a few months it was warm enough today that I could roll down my windows. The rear windows work on the buttons on the door, but niether the front or rear windows work from the center console. I did have a stereo installed by a reptuable shop just about a month ago and plan on calling them today since they told me they had to by pas the little wheel fader in the center console and the amp. I just wanted to see if anyone ellse had any suggestions for me to look into in the mean time. The fuse blows as soon as the key turns the ignition.

Unplug the connectors of the window switches and try what the fuses do. If they don't blow, you can plug connector after connector to see when the fuse blows. It will point you in the proper direction to seek.

The fader switch has a LED for the dash illumination; maybe they messed up something with that (although I cannot imagine what).
The 1991 300D power windows are quiet easy to work on.
Maybe one of the connectors in the doors is being shorted (I believe that the US models have speakers in the front doors???). The 2 wires of the electric window motors are attached to the wire harness (to the switches) by a screwed connection in the steel door panel.

greetingz,

Was everything (windows) working before the stereo was installed? If they were, then, they messed up something in the console wiring. The windows are fused in pairs. Opposite corners together, ie. R front and L rear. If nothing works and the fuses continue to blow, there is a short in the console. If, as you say, they work from the rear window buttons and the fuses don't blow, then the wiring in the console is definitely messed up. BTW, which fuse is blowing? And, if it is blowing when you turn the key, then how are you getting the rear windows to operate? I'm a little confused by your description, but that's OK, because I'm always a little confused about something, or so my spouse tells me. :D

JEFFSR,
The fuse that blows is fuse "G", it says "window lift front". It blows as soon as I turn the key. With the blown fuse, still in the car, the rear windows operate, but only by the buttons on the door, not the buttons on the console. The stereo place only put the head unit in and the installer seemed very knowledgable about MBZ's. I spoke to them today and they scheduled me for the first appointment for Monday morning. I did also just replace the battery since the car was not firing up instantly. It turned out that the battery was 11 years old and original. (WOW!!!) Is there perhaps a voltage regulator that may have blown?
What are your thoughts?

Well on that year w124, the windows are fused on opposite corners. The G position is for left front and right rear. Take another look at the fuse schematic on the inside of the cover. Unless they have changed it, should say window lift left front a right rear or something like that. I beleive they designed the circuits that way to avoid heavy current loads on one circuit, ie lowering both windows on the same side at the same time. Anyway, if G is blowing when you turn the key, the right rear should not be working.
But, you say that it is by using the rear door actuator button. If your fuse schematic says there is only one fuse per window, try and identify the other three. I don't think you will find them. Don't think it's a voltage problem. There are other systems in the car that would take a hit if that were the case. I'll look in my manual of schematics to see if there is a relay involved, (think there is).

JEFFSR,
I double checked the box and it clearly says "window lift front" and then it has a second fuse that says "window lift rear". I do stand corrected, both rear windows work on the door buttons and only the RR works on the center console panel. I could do some trouble shooting hear myself, but I first want to see what the stereo people find out. The windows worked perfectly when the car went in, therefore I have a strong suspicion that the source of my problem occured while it was in the stereo shop.

I think you are probably correct. Does the G position control the rears? If they have changed the wiring since 1989, it's good to know this change. Thanks..

No, fuse G is only the front. I looked at my Cd and I do see that for early 124's it is a criss-cross pattern, but not on mine.

Well here is the update, it is not the stereo and they even pulled out the switches for process of elimination. I guess I will disconnect the window motors and keep tracing each device back to the battery. Any suggestions would greatly be appreciated.
:)

Does anyone have any advice on how to test for a short, by using a multimeter?

If you are trying to locate a short, I use a device called short finder as I posted few weeks ago. Seach the words "short finder" to find my post.

David

be459,
I did a search as you suggested, but came up emptyhanded. Can you post the link?

be459 where are you?
 

Where are you be459???

CJ,

I don't know where be459 went, but this is the post he ment (I think).

http://www.peachparts.com/shopforum/tech-help/14232-i-cant-find-my-shorts-fuse-problem.html

greetingz,

Finally the solution
 

Well, after trying to trace the short, I called over my friend Eric, who has a degree in electrical engineering. He looked at the wiring diagrams and made an educated guess that the "convenience module" under the rear left seat was bad. After performing a few test and then a trip to the dealer to plug in a new module, voila, we have power front windows. I did not buy the new module, due to the lack of funds, but my problem is solved.
Damn this guy is good!!!!