Why Are My Power Windows Working Intermittently?

Electric power makes window-rolling easy. It can be a pain to roll your windows with a crank, and driving’s easier when your window motor does it for you. Until it works only when it wants to. Why do power windows do this? And what can you do to fix it?

Depending on the model and the options that you have on your master power window switch panel, one of three or four parts will cause the issue.

The Computer

Some vehicles have a slew of power options that send signals to the computer from the switch. Sometimes it's just the computer that's faulty, intermittently sending signals to your motor, and leaving your windows only working part of the time. As you may have guessed, automotive computers are pretty complicated. If you have problems with your computer, you'll probably have to take your car to a reliable shop to get your issue sorted out.

The Switch

Sometimes the problem is with a defective switch, and sometimes it's with a defective connector. You can pry the window switch up from the door panel and disconnect the connectors. Check the wiring harness for corrosion. Sometimes this can be cleaned, and sometimes it will need to be replaced. If the connector is fine, it may be the switch. Moisture is tricky and can sneak inside the switch and connector if outside elements manage to get in the door panel.Replacing a window switch is a pretty easy repair. You'll just have to pry the switch panel up from the arm rest using a trim tool and then unplug the wiring connector. Depending on your car, you may have to replace the entire switch panel as one piece or you might be able to separate the failing switch from the panel and clip in a new one. Then, simply plug the switches back in and press them back into the armrest.

The Window Motor

If the motor is dying and is partially receptive to power or it has a bad ground, your windows may only work some of the time. A bad ground can be fixed by cleaning corrosion on the surfaces of the contact points of the door and the ground. If the motor itself is burned out (it can happen over time, or do to extra strain from a misaligned window or regulator), you can replace the motor, by disconnecting it from the window regulator and installing a new one, or you may decide to replace the motor and regulator as a single unit.

The Wiring

Sometimes there can be a short circuit. Insulation on the wiring can break or tear over time, and this can expose the copper wiring/conductor. A weak connection can lead to a weak electric current or the wire can separate completely, maybe only touching when you drive over bumps. This can lead to an intermittent connection, but depending on how bad the corrosion is, you can fix the split by crimping the wire with a butt connector or by soldering it. Sometimes you’ll have to replace the wire entirely.

How to Test

If you’re unsure which part is defective, you can test the electrical connections with an inexpensive test light or voltmeter. Simply pry up the switch, turn the vehicle on, and probe into the power wires entering the switch connector. If the light brightens or the meter reads the right voltage (usually 12v), then you know there is power going to the switch. Then test the wires leaving the switch. If the light brightens, the problem could be with the window motor or the wires leading to it. If you have no power at the switch, it could be either the window switch or the wires leading to it.


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