The seat motor on your BMW Z3 allows you to move the seat to a position that is comfortable for you. If you find the seat is no longer moving you should replace the fuse, a simple procedure. If that does not solve the problem you may have to replace the motor. That requires you to first remove the seat which can take some time. Although the seat motor is not essential for driving your Z3, it does make the ride much more comfortable.
Open the bonnet and remove the cover from the Z3's fuse block.
Remove the fuse from slot 14 and install a replacement 30A fuse. Reattach the cover to the fuse block. If the power seats are still malfunctioning, you may need to replace the motor.
Slide the Z3's seat all the way to the back and use a socket wrench to remove the retaining nut from the front of the seat. Slide the seat all the way to the front and remove the two bolts at the rear of the seat.
Unplug the two electrical connectors of the Z3's seat and remove the seat from the vehicle.
Use a flathead screwdriver to remove the four clips from below the seat, retaining the cushion with the metal part of the seat. Remove the two Torx screws with a Torx screwdriver and remove the cushion from the seat. Once the cushion has been removed, you can locate the seat motor at the bottom, right corner of the seat.
Remove the four Torx screws from the seat motor and disconnect its electrical connector. Remove the motor from the seat.
Place a replacement motor onto the seat and connect its electrical connector. Reattach the four screws.
Reattach the cushion and its retaining screws and clips. Reconnect the electrical connectors to the seat and place the seat back into the Z3. Reinstall its retaining nut and bolt.