How are door window motor issues diagnosed?
A technician will being diagnosis of a faulty window motor by actuating the switch and listening for sound from the motor. If there is no sound, a technician will first check the relevant fuse. Next, a technician might observe the interior dome light while operating the switch. If the dome light dims, the motor is likely to be broken. For final verification of a bad motor, the door trim panel will need to be removed so that the wiring harness connector to the motor can be checked for voltage. A technician may even be able to use a professional diagnostic scan tool to locate a potential problem with the vehicle's wiring in a late model vehicle.

How is a door window motor replaced?
Replacement of a window motor depends on the type of vehicle and style of window regulator. Generally, a technician will remove the interior door trim panel, taking care not to damage the latch cable or any electrical wiring that is attached. Next, the door vapor barrier is removed. The window is disconnected from the regulator (this may be difficult if the regulator or motor are not functioning properly) and either held in place or removed from the door. Finally, the regulator is removed from the door and the faulty motor is exchanged for a new one. If the motor is integrated into the window regulator, the entire assembly will have to be replaced.
RepairPal Recommendations for door window motor issues
RepairPal recommends that a repair manual be referenced before removing an interior door trim panel to prevent damage to the retaining clips, electrical wiring, and latch cable. On some vehicles, the window regulator may have to be replaced with the window motor. A manual can also give important information for resetting the control module on some vehicles.
What to look out for when dealing with door window motor issues
When replacing a window motor it is important to be aware of any electrical wiring that might run between the interior door trim panel and the door shell. It is easy to break sensitive electrical connectors when removing the trim panel. There is also a door latch cable that needs to be removed; the cable can break if care is not taken when removing the trim panel. The panel is held on to the door in most cases by screws, bolts, and plastic clips. These clips are "blind" - they cannot be seen from the outside of the trim panel - and in some cases are "one time use" fasteners. Some manufacturers require a reset of the electronic module that controls the windows after a window motor has been replaced. On some vehicles, there is an airbag mounted behind the door trim panel; naturally, extreme care should be exercised when working around Supplemental Restraint System (SRS) components.