Power Window Wiring Failure notice

This problem is starting to show up more often as all these old Mercedes age. So I thought it was a good time to post it on our website. This will give you a clue as to what might be happening with your power windows especially if they are showing weird signs or intermitted operation. The problem occurs after countless hundreds of times of opening and closing the door the wiring bundle that goes from the door into the door post will become brittle and the wires will actually break. When the wires break they may only make contact especially when the door is closed. You may find when the door is open your window wont go up and down. Worse yet I've seen these wires on some occasions start cross connecting and blowing fuses. What makes this most frustrating is it can be very intermitted. Sometimes the windows will work, sometimes it will blow the fuse, sometimes it won't blow the fuse and you may be replacing window motors or switches and be totally frustrated because you can't find the problem.

The problem can often be found in the wiring between the door and the door post. The wiring actually flexes in this area (when the door opens and closes) and will break over time. As you can see in this picture of a 201 chassis 190E all four wires were found clearly broken. For some reason this seems more common in the 190E's than in other chassis. But I have seen it show up in 123s and other chassis through the 80s and into the early 90s. Just be aware if you are experiencing weird intermittence power window failure and fuse failure then you might want to pull the doorpost covers and inspect this wiring.

NOTE: you will have to cut the braded installation back from the wires using a razor blade in inspect for breaks in the wire(s). To repair the problem you will need to install new lengths of wire that you run through the door post section splicing them up back close to the plug and splicing them once again down into the inside of the door post where there is no flex.