BMW E34 power windows, sunroof and central locking stop working
Why do the E34's power windows, sunroof and central locking stop working at the same time?
The most common cause is the main fuse. It is an aluminium strip in a black plastic housing under the rear seat, and it can have a thin crack, for example under the mounting nut, that you cannot see from above. A new fuse often fixed the radio, wipers and instrument cluster symptoms as well.
What else should I check if the main fuse is fine?
Check the wiring harness connections and the ground under the rear seat, because they oxidise and can break. A wrong general module (the control module under the rear seat) or relay module will also leave the windows and locks dead. Fitting the correct module fixed the fault.
What jams the E34 sunroof?
The most common faults are a broken pin in the sunroof frame, a loose or snapped drive cable and worn rails. If the gears of the front motor have stripped, the motor must be replaced. The sunroof is heavy, so get a second person to help with removal.
How do I reset the sunroof if it was left open after disconnecting the battery?
Press the middle of the sunroof switch for about 10 seconds. After that the sunroof closes normally.