Power window problems on cars and trucks could be considered one of the most annoying problems you could have on an automobile. When you think about it how often do you actually operate the power windows on your car.
When you roll up to the drive-through window at your favorite fast food restaurant or you are going to pay a toll I’m sure you would like your window to operate properly. Many times electric window operation can become intermittent. This is even more frustrating than if it stopped working altogether.
When you have intermittent operation the tendency is to put off repair of the system until either the problem gets worse or the Windows stops working all the time. From a safety point of view you really shouldn’t put off repairs because you never know when rolling up or down that window will be important for safety reasons.
Power window systems
The power window system happens to be one accessory that really doesn’t vary that much between vehicle manufacturers or car models. The major components of an average system would be the master switch, the window lift motor, circuit breakers and relays, and the wiring that ties those items together. Oh I forgot the glass itself.
Often when the window stops working people ask me where the fuse is. Most modern power window systems do not actually have a fuse. It is more common to find a circuit breaker protecting the wiring and electrical components. A circuit breaker will automatically reset if the system overheats or pulls too much amperage.
In addition to the main circuit breaker usually there is an internal circuit breaker to protect each individual window lift motor. If one of the window switches is held too long or the window is obstructed the circuit breaker will automatically open to prevent damage to the motor.
Common problems with power windows
I diagnose a lot of these power window systems. The two most common problems that I find is either a defective window lift motor or a problem with the master switch. To break it down even further it is the driver side window motor that I see fail most often.
The simple fact is that the drivers side front door window is operated much more than any of the other Windows on most vehicles. This is also true with the master switch that is usually mounted on the drivers side door panel. The master switch gets more use than the other switches in the vehicle.
On my own personal vehicle the master switch is mounted flat on the driver side armrest on the door panel. I have had problems with the master switch because of its location. Water from the roof drips right onto the switch when the window is down or even partially opens. This poor design led to heavy corrosion built-up inside the switch.
I was able to save myself from replacing the switch by removing and disassembling it. I got myself some electrical contact cleaner and was able to remove all of the corrosion. I have to perform this procedure about once every two years because of this master switches poor location.
Diagnosing electric windows
Just because the driver side master switch and the driver side window lift motor are the most common failures this doesn’t mean that you will have those exact problems. Many other parts of the system are capable of failing.
When you’re starting your diagnosis of a power window system it is best to determine if the whole system is not working or maybe it’s just one window from one switch. If nothing works in the system the place to start would be with the master control switch or the main system circuit breaker.
If only some of the Windows don’t work and others do you would want to check parts that are common to the windows that are not working. From an electrical point of view you may need a wiring diagram for your specific automobile to determine what electrical parts are in common.
As an example let’s say that the right rear window is the only window not working. It does not work from the master switch or the switch on the right rear door panel. In this case it would be time to remove the door panel and inspect the power window motor that runs that window. Again an online auto repair manual will provide step-by-step diagnostic instructions to determine what the failure is.