Power Window Repair

Power window repair is not terribly difficult in a lot of cases, even for the novice home mechanic if he or she takes their time, has a little patience, and has access to a factory service manual or a subscription to ALLDATAdiy for their particular vehicle.  If you have a very basic understanding of how electricity works and a little mechanical aptitude, you can test the circuit to a power window motor and determine if the fault is in the motor, a switch, or a relay.

First, which window is it that isn’t operating? If it is not the driver’s window, does it work with the driver’s master switch but not with the passenger’s switch, or vice-versa? If one switch makes the car window motor work and the other one doesn’t, the most likely candidate is obviously the switch, but it still could be the power window wiring or a relay. Test the switch by pulling it out of the door panel and checking for power on the wire going to the motor (consult a Factory Service Manual or ALLDATAdiy).

If it is not the driver’s window and neither switch makes the window work, the next step towards your power window repair is to either test the relay or remove the door panel for the offending window to see if the motor is getting power.  If it is the driver’s window, you most likely don’t have a second switch to try, and you will have to then check the switch, the relay and then the power window motor.

A bad motor is fairly easy to diagnose in most cases.  First consider the symptoms and the history.  If the glass that has the problem has been slow going up or down recently, the car window motor is definitely a suspect.  If you can hear a click or a hum inside the door panel when you operate the switch but the glass doesn’t move, that is a pretty good sign that the motor is bad.

Sometimes when a power window motor fails, you can get the glass to move by pounding on the door panel with your fist as you operate the switch.  If it is the driver’s window, you have to keep in mind that pounding on the door panel that contains the only switch could make a bad switch work.  Pull the switch out of the door panel to isolate it from any vibration it would get from you beating on the door panel.  If the glass moves when you beat on the door panel, the motor is the most likely candidate.

If pounding on the door panel doesn’t make any difference, then remove the door panel and see if the motor is getting power (and has a ground) when you operate the switch.  If the switch tested good but the motor doesn’t get power, then the fault is in a relay, the power window wiring, or a bad connection.

If the motor has power and ground and you can see that the motor turns on but the glass doesn’t move, make sure the glass hasn’t come out of its track and that there aren’t any loose fasteners allowing the glass to get cocked and jammed up in the track.  If you don’t see a problem with the power window regulator and the motor has power and ground, then a power window motor replacement is in order.


*** What is the best source for auto service and repair information – a factory service manual, ALLDATAdiy, a Haynes or Chiltons book, or ??? Check out my page on Auto Repair Information to find out the pros and cons of each.

This general methodology will work to determine what car power window repair needs to be made on most vehicles, but it is always best to consult factory service information for more specific tests.  There are many different power window parts including relays, circuit breakers and/or fuses that could be at fault, and every vehicle is different in how the circuits are designed.  Some vehicles have a “child lock” feature on the master switch that could be at fault, and some vehicles have a body control module that can fail.

If you get stuck, it is always better to consult factory service information that to guess at the problem and start replacing power window parts without properly testing the system components first. I hope this car power window repair tutorial has helped, but it is no substitute for the diagnostic procedure laid out in a service manual or on ALLDATAdiy.


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