The park brake motor is referenced in the following service manual. If the car shows errors like Park Brake Fault and Parking brake requires service it may be caused by a broken motor, even if the car is still able to park most of the times.

If this error message is shown on the display, it may happen that the car does not switch off, when leaving the car. Also, nothing happens when pressing the two steering wheel buttons at the same time to reset the system. So far, the only solution is to disconnect and reconnect the 12V battery.

Things to check and to do:

• Verify if the parking brake pads are stuck or are still be able to move.
• Verify if the park brake caliper motor (can be found on Ebay or Amazon) with search terms like PARKING BRAKE CALIPER MOTOR for Tesla Model S X 2012-2021 1621620888C 40C07812 shows signs of wear, corrosion. This applies especially to the visible gears. The motor can be easily removed with three TORX T-25 bolts. Please take care of the rubber O-ring seal and the recess at both the motor itself and the brake caliper, which must be thoroughly cleaned to prevent water ingress. There are numerous videos on youtube showing this process.
• Replace the Park brake Controller ECU (TPN: 1007618-00-D) which is mounted in the trunk, at the rear on the right side, behind the fabric, as shown with the following video (beginning at 12:16), following the official procedure from the Tesla service manual. The replacement module was a revision E (TPN: 1007618-00-E) which seems to reduce the frequency of the errors being shown. After replacement perform an update of the vehicle firmware via the service menu.
• Verify the cabling between the park brake caliper motor and the Park brake Controller. (Refer to Tesla Service Manual wiring diagrams
• Measure current through the motor. When there is no load on the motor, it will draw a current of about 1.2A @ 12.0V.