Mercedes power window repair
Contents
References
- Overview and failure modes
http://www.youtube.com/watch?v=10PqXN7FZUQ
- Power window wiring troubleshooting
https://mercedessource.com/problems/interior/power-window-troubleshooting
- long video of removal, repair and replacement of power window regulator for a newer model (shows how to apply power to the motor to test)
http://www.youtube.com/watch?v=R81Q4FzXlOc
Right front power window repair
Image of window motor.
http://www.partsgeek.com/assets/rep/full/1012983.jpg
switch continuity test
There are four pins for each window switch. On bank of switches controls a front and bank window. The driver side also has a child lock with an extra two pins. Measurements are on a front right window and were verified on a front left window. (The back windows appear to have a different pattern.)
O = open circuit + = closed circuit
rocker at rest
| A | B | C | D | |
|---|---|---|---|---|
| A | O | O | O | |
| B | O | + | + | |
| C | O | + | + | |
| D | O | + | + |
rocker forward, window up
| A | B | C | D | |
|---|---|---|---|---|
| A | O | O | O | |
| B | O | O | + | |
| C | O | O | O | |
| D | O | + | O |
rocker backward, window down
| A | B | C | D | |
|---|---|---|---|---|
| A | O | O | O | |
| B | O | O | O | |
| C | O | O | + | |
| D | O | O | + |
Verified that the switch is operating properly. But the window still doesn't show any sign of life when the switch is pressed.
test window motor
Tips for fixing windows: http://www.benzworld.org/forums/w123-e-ce-d-cd-td/1653133-300td-console-window-switch-help-please.html
If you need to get your Widow up you need some Jumper Wires to connect to the Battery (easier to pull the Battery out). Touch one wire to each of the Terminal/Junction Block Screws and the Window will go one way. Swapping position of the Wires and the Window will go the other direction. The Window Motors do not use the Chassis ground as part of their circuit like the Starter Motor does.
From that same page:
Somemore thoughts on Power Windows. If the Window Motor does not work when you connect it direct to the Battery it is often the Motor Brushes worn out. People have gone in and replaced those.
On the Rear Windows if they go up and down and make noise the Window Regulators back there bend. Can also be the above if the Motor turns but the Window does not.
Window not working at all can be due to the Wires breaking where they Hinge at the Door.
If all of the Windows shop working the Power Window Relay shares a Fuse with some other components. You need to look at your Fuse Chart th find which one.
Window motor diagrams: http://www.partsgeek.com/catalog/1983/mercedes/300td/body_mechanical_-ar-_trim/window_motor.html
door interior photos for disassembly
motor test
I tested just the motor by using jumper cables and short wires to apply power from the battery directly to the terminals near the motor. The motor worked and could drive the window up and down.
Then I checked the fuses and found that it was a simple blown fuse. I was fooled by the fact that some of the windows worked, so I didn't bother checking the fuses earlier. Front right and rear left are on one fuse and front left and rear right are on another fuse.
Left rear power window repair
Even after the fuse repair, the left rear window still doesn't operate. I took the door apart and found that the regulators on the rear doors are very different. For one thing, they don't have an easy to access terminal to test the motor. I couldn't even find the motor. It must be in the left side of door in a deep corner of the cavity without any direct access.
- verified that when I swap the switch for the left rear window with a working window, the left rear switch is able to operate properly. So the switch is good.
A replacement part for the regulator looks like this:
http://www.partsgeek.com/assets/rep/full/1021467.jpg
The replacement motor looks like this:
