jedcred

An odd problem just started right after (more than likely unconnected, but FYI) I got my tires rotated and balanced. The passenger window acts funny. Here's what it does:

- If you press auto-up or auto-down (pull or push all the way on the switch), after approximately one second, the window goes all the way down or all the way up.

- If you pull or push the switch halfway (to adjust its height manually), the window waits for approximately two seconds, then will move in the proper direction about four inches, stop, then continue. Where it stops on the up and down traversal seem to be the same spots.

-This only happens with the driver's side control; the passenger side control works completely fine.

So, when I noticed this about five minutes after starting the car, I pulled over and tried the passenger side control (which worked), though the driver's side control continued this odd behavior. I tried a resync (hold up and hold down for several seconds to no avail). I shut off the engine, pulled out the key, waited about a minute, then started up again, with no change.

I went driving down the freeway, and after about 5 minutes, it worked fine again! This was the case all the way home. It has never once exhibited this behavior before.

Since I'm almost out of warrenty (5k miles left), I'd like to fix this problem now if it wasn't some sort of fluke. Could it be the window switch, window regulator, or control module?

Thanks for your time.

loungn14

Dont know if yours is the same as mine (c32) but it seems like the windows have some sort of strange memory or something.....

I changed batteries, and was getting close to the same symptoms. Roll all windows all the way down and all the way up a couple of times and all should be good to go. (sunroof as well)

jedcred

As part of service A, I asked the dealer to look into the window issue, for which they "resynced" it. It didn't reoccur until today. This time I had the presence of mind to take a video with my phone, so you guys could see exactly what was going on.

During this video, remember that I'm constantly holding the switch either partway up or partway down, depending on the direction of traversal.

Click here for the video.

Moviela

Moving the window is not as simple as touching a switch connected to a motor in the C class. Each door on the car has an electronics module, about the size of a sound card. The window switches on the door is connected to an input to a mocrocontroller in the door module. In the case of this car the signal flows from the fingertip to the switch on the drivers door. A contact closes in the switch that is "read" by the microcontroller. Software in the microcontroller knows that contact is for the passenger side, so it sends a data byte to the canBUS that in effect says "The driver has pushed the passenger window switch, how about a little service?" The canBUS then sends a command to the passenger door module microcontroller. "Start moving the window down and await further instruction." The next instruction will depend on what the fingertip is doing. If it has come off the switch, the canBUS tells the passenger door module "All the way in one play, its an auto-down signal." If the fingertip lingered, a command would be sent saying "Keep moving until I say stop, or you are at the bottom, which ever comes first."

If the fingertip comes off while the window is in motion, the canBUS crosses the batons for a full stop.

The door microcontrollers have a signal output that operates a mechanical relay to move the window up and down. The microcontroller measures the current flowing in the motor to determine when the window is down. When the window hits a stop, up or down, the current goes up. The microcontroller uses this information to determine when to stop running the window motor.

In jedcred's car there can be a couple of bad actors. A bad switch contact can cause the window to stop in the middle. The switch can be dirty and intermittant, or spilling a beverage into the switch can gum up the works. Next is the wire from the switch to the driver's door module. Next, the canBUS wires from the driver's door module through the hinge to the car body. With the driver's door open, move the passrnger window while wiggling the wiring harness from the door to the body to see if the canBUS wires are broken in the harness where it flexes everytime you open the door. Next take off the door panel and check the cables going in and out of the door module, and the connection to the window switch. Finally remove the switch from the harness and test the contacts for continunity.

If you have a warranty, don't do anything, just tell the service advisor the window is not responding properly.

jedcred

Thank you Moviela; detailed and helpful as always.

I am under warranty, but unfortunately my local MB dealer is not . It's an uphill battle to get them to replace anything, or to give you any sort of true service (such as an MB loaner, for instance) if you drive a lowly C class, or even an ML. I'd like to go armed with some possibilities so that they are forced to check it out. This is untrue, however, of Stead Motors in Concord; however, Concord is a 45-minute drive for me as opposed to a 5-minute drive. Hopefully they'll look into this problem more seriously this time, but if not, it's off to Concord again for some quality service.

Thanks again.

jedcred

An update.

After three separate trips to the dealer, this issue seems finally fixed. The last thing they replaced was the driver's side window switch, and things seem to be working now.

For future reference, it is a great idea to take a video with a camera phone with a problem like this to show it to the dealership mechanics. I showed the actual problem to one SA in person, described it to another, and they still called me in to speak to the mechanic, who started describing something completely different. I decided to make things easier for everybody and I showed him the video. He said he'd never seen anything like it before, but he had a better idea of what I was talking about. Lifesaver, that.

In the end, I did get a new passenger window motor out of it, though that didn't fix the problem. Anyway, FYI.

e1000

video phones FTW!!!!!!!!

jedcred

Indeed.

So it started again, and the car went back a third time. Latest (and hopefully final) diagnosis is a wire terminal # X35/1. Apparently it was throwing an error code of B1093, which is interesting, since the previous two times the SA specifically stated that no code was being registered with the computer. Whatever. As of now the problem has not resurfaced, but hopefully if someone else has this problem in the future they'll be able to track it down faster with this information.

saa3442

my driver window stuck in up position, taken to the shop, replaced the switch, tested the controller, etc, etc, etc, i finally found that the wire terminal that goes into the motor has the hot wire broken inside and will not make connection. this must have happened as the stress on the wires rapping around the door metal frame "it was tight". i discovered it when i tested the wires for current flow. any one knows where i can get a connector or inexpensive harness? - Louisville, KY