Mercedes power windows

Mercedes power windows — Diagnose and repair

Mercedes power windows issues can be either mechanical or electrical. If you’re dealing with funky operation where the window moves but not in the manner you expected, chances are it’s electrical, not mechanical. For example, most late model Mercedes power windows have one-touch opening and closing and anti-pinch features that can goof up if power is lost. That’s because the controller keeps track of where the window is in the channel using a Hall effect sensor in the window motor. If it loses power, the controller forgets its memory.

Mercedes power windows relearn

When the window memory is wiped out, Mercedes refers to this as denormalized, which calls for a relearn procedure. To relearn pull the window button up and hold it in the up position until the window is in the full up position and continue holding the button up for a full second after it stops. Then push the button down and hold it down until the window is in the full down position and hold the button down for a full second. This relearn procedure establishes the full up and full down reference position.

For that point on, the controller counts the number of revolutions on the window motor to determine the exact position of the window. Each window has its own controller.

Mercedes power windows denormalized

A blown fuse, intermittent wiring or a bad window switch can cause the window to become denormalized. If the window doesn’t operate at all, check the fuse or circuit breaker for that window. Then check switch operation. IF the switch is getting power and ground, check the wiring harness for an open or intermittent condition.