electric window issue 99' E300TD
 

Just the other day I started having an electric window issue. It is my rear window on the drivers side. I mashed the switch button up front and nothing happened. So I mashed the switch button on the rear door and nothing happened. Prior to this the window seemed to be working just fine. The motor sounded normal, and it wasn't acting sluggish or anything like that. About a day later the same window started working fine again from both switches, but now it has stopped working again. Could this be a relay or something? Any help diagnosing this problem would be greatly appreciated. Thanks.

The usual problem is the regulator breaking, but of course once the regulator breaks, that's it.
Would tend to think the window motor, or maybe wiring in the door hinge area.
Gilly

When mine acted that way it was the "motor module" (CAN). It seems that was a common problem. I got another out of a wrecking yard and so far so good.

Replace or clean and reinstall your fuses. Might just be some corrosion.

Thanks for everyones replies so far. mpolli, what exactly is the CAN, and where is it located?

The CAN bus is a serial data bus that controls accessories on new cars. That way they don't have to run power wires from every switch. On the motors there is a CAN transceiver module that receives the commands to go up or down. It is integral with the motor. So essentially you would change the motor. However, I don't think anyone sells just the motor. They do however sell just the cable/track mechanism so if you are buying aftermarket be careful what you are getting. I cannot guarantee that is your problem but the symptom is the same as I had and I think MB Doc would tell you the same thing. Maybe he will chime in on this matter.

Actually I guess I got lucky. The link off this website to allpartsexpress.com has the genuine MB window motor for the left side for $137.00, which is the side thats broken. For some reason its about $50.00 cheaper than the right side.

I have changed out entire window regulators before on domestic vehicles but never on the MB. Is it difficult? Is removing the door panel tricky? Thanks.

That is lucky! I would think they would be the same motor as my car but I guess not. Anyway, I think you can find quite a bit of info on this by searching but basically this is how it goes:

First remove the door panel. This can be a little tricky the first time so search for the instructions for that car.

Once you have the door panel off you have to peel off the plastic liner to have access to the window regulator. You must drill out the rivets that secure the window regulator to the door. I used a 1/4" drill to drill the head off, then punched the rest through with a center punch. Then remove the plastic clip at the bottom of the window. As I recall there was a white piece of plastic (the "clip") that I pulled down (or up?) and then then there was a plastic "cam" on the bottom of the window that slid out of a "channel" on the regulator. I did all this with the window up which seemed to be best, and I put a piece of tape on the glass to hold the glass up while the regulator was out. The motor is held on with 3 big Torx screws and comes off easy. Put the regulator back in and attach to window before riveting of course. New rivets are pretty cheap and you should have ordered those at the same time you ordered the regulator, otherwise you can get them at the dealer for about 1.50 each. You need an extra big rivet gun and a strong grip! When you are all done be sure to reseal the plastic film so it is waterproof. Ask me how I know this... Good luck

Is it necessary to remove the regulator to change the motor?

I'd open it up and see what part failed first.

Mine ate my replacement regulator. The motor is fine, but bound up by the reg and doesnt make a sound when either set of switches is pushed.

That is a good point. I can't remember and mine is a different car anyway. But maybe you could.

That is also a good point. It seems they fail about 50/50 motor/regulator. I never said it was the motor, just that the symptoms were the same as when my motor failed and M B Doc said that was the problem and it was. He did say it worked fine then died then worked fine then died. That doesn't really sound like a bad regulator but I suppose it could be. It certainly wouldn't hurt to take a look first.

Seems to me you can't take the motor off with the regulator installed. Make sure you get the big kahuna rivets that hold the regulator to the door. Although you need this big kahuna rivet "gun" to install these rivets, which probably will involve a favor from a body shop to get done, so I might suggest replacing the rivits with nuts/bolts/lockwashers.
I would disagree on the 50-50 failure rate of motors to regulators. Usually it the regulator that breaks, where the pivot is that joins the regulator to the window, probably about 75% of the time, this is the failure. The window will stop going all the way to the top first (that's when it first breaks), then it stops all together.
Gilly

Thats been my expirience twice. A minor crunch or two, then nothing.

I used SS screws and some nuts to put it back togther. I know Matt L tapped the hole which would also work.

Good to see you posting Gilly.

I had an old Craftsman rivet gun that had interchangeable tips and one was big enough to handle the kahuna rivets. However I got Carpel Tunnel syndrome after doing 1 or 2 (at least it felt like it...) I think bolts would work as well but I would use loctite or nylocs probably.