1999 E300D Driver's Window Inoperable
 

My wife had someone try to jump start her 1999 E300D and inadvertently reversed polarity (how does someone do this when the cover on the inside fender has a BIG RED POSITIVE symbol?) resulting in quite a few blown fuses that I have all replaced.

Everything on the car works as it should with the exception of the driver's side window.

I know it's not the regulator or motor as I have replaced many of the both of them on practically every Mercedes that I've owned.

When I press the window switch a discernible clicking sound is heard from the plastic black box with a connector with wires going to it that is visible with the door panel removed.

Is there an electrical testing procedure that I can perform with my fluke meter to see if the plastic black box is the culprit?... I am an electronics tech so I know how to use a meter thoroughly.

Thank you,

The window controls on a W210 run off the body CAN bus. When you press the switch in the center console (known as the lower control panel in the service manual), you are creating a CAN bus message to tell the door control module to operate the window motor.

I would see if the motor is getting 12 V dc across its terminals when you push the switch. Remember this will be using an H bridge circuit with relays (or maybe MOSFETS), so it can flip the polarity to run the window up or down. So you’ll need to measure across the motor terminals and not to ground.

If you’re not getting voltage out try disconnecting the motor controller from the motor and jumping 12 V and ground to the motor leads. If the motor runs the controller is shot. Fortunately these are not VIN specific and require no programming. So any W210 in the yard should have the same DCM part number in its drivers left front door. They are hard coded to their location, so you can’t use a right front, it has to be a left front.

Or of course you can try cracking open the case and see where the magic white smoke came out...

Thanks jay bob, would disconnecting the battery for a while and reconnecting it possibly reset the can bus???.... I ask this because at one point the battery had become very low when I was cranking to bleed the fuel system.. I had to charge the battery

Hey jay bob!!

I followed the diagnostic process that you posted to the letter and by isolating each component it was revealed that though I can here the black box clicking when ever the window switch is pressed, it is not transferring the power to the window motor as commanded.

I located a replacement, it is described as a door control module!

Don't know if you resolved your window problem yet, but over the years, I occasionally have had an individual window that didn't work on my '84 190D - typically, it is the driver's window. Every time, it was the switch in the console in between the seats that was the source of the problem. Removing the switch from the console and opening it up is pretty evident just from examining it. If you've never opened a window switch up, just be careful to do it over a plate or pan because it contains parts and small balls that may fall out if you don't hold it upright. I simply cleaned all internal parts and put it back together, and that fixed the problem every time. Whenever I have a problem with my car, I always start with something simple initially. My car is 34 years old and all the regulator motors are still going strong. Good luck with that!

Replaced the door control module and when the window switch is depressed I can hear two audible clicks coming from the module but the window still does not operate. The old module only would click once so it appeared initially that the new module would solve the problem.

I verified 12 volts DC going into the middle of the relevant connector on the thicker gauge wires that are for the window motor operation. I also verified that the power is going down to the window motor when I press the window switch for the down command but the test light only lights up momentary (about one second) but the window doesn't budge. I also verified the window motor and regulator work flawlessly by unplugging the connector on the window motor and directly feeding 12 volts DC, the window goes up and down when I switch polarity.

I am at my wits end, any suggestions will be greatly appreciated because this is starting to drive me crazy!!!

ps, to Baby Benz Sanda, this is a 1999 E300D and the power doesn't go from the switch to the window motor like it does on yours..... On a 1999 E300D it's being done by data