Window goes up but not down, window goes down but not up
Or, your power window only works from one switch
Ok, so you think your power windows are possessed. They’re not. But what most people don’t understand is that all the power and ground connections run through the driver’s side master switch, and that really complicates the trouble shooting process. Here are the three trouble spots:
1) master switch
2) broken wires in hinge area of door
3) passenger switch
4) window motor
5) broken window regulator
The easiest way to approach a problem like this is to first check the fuses. I’ve drawn a wiring layout for an early 2000 Ford vehicle.
It’s fairly typical of how most power window systems work. If you click on the illustration, it’ll pull up a 2-page PDF. Flip from page 1 to page 2 to see the difference between operating a window from the master switch versus the passenger switch.
Notice that power is provided by two fuses. The power from one of the fuses is switched by the accessory delay relay. Car makers do that so they can prevent power drain from window operation during start up. That’s where you start your test—to see if you’re getting power from both sources. Later, you’ll see how that might affect operation and cause a window goes down but not up, or window goes up but not down, or window only operates from one switch. Got power on both? Good. Now let’s test the rest of the system.
Let’s assume the front passenger window doesn’t work from the passenger switch. Pop out the passenger window switch and disconnect the electrical connector. Using a digital multimeter , connect one lead to ground. Then operate the master switch for that window and probe the pins in the disconnected electrical connector to see if you’re getting power. If you are, then flip the master switch in the opposite direction and probe for power on another pin. Once you find the two pins that provide power, insert a lead in each. Then flip the master switch back and forth.
The readings on your meter should toggle between +12 volts and -12 volts. If so, then the problem lies in the passenger switch, the wiring between the passenger switch and the passenger motor, or the motor itself. To find out which it is, reconnect the electrical connector to the passenger switch and remove the door panel. Then disconnect the electrical connector from the motor. Attach your meter leads to the electrical connector and toggle the passenger switch. You should see +12 volts and -12 volts. If you do, then the motor is bad. If you don’t then check for an open in the wiring or a bad switch.
If you’ve tested the passenger switch and don’t the results I’ve shown, you could have a broken wire in the hinge area of the door. These wires flex every time you open and close the door and they do break. The other possibility is a bum master switch. If you haven’t already done so, NOW is the time to buy a good wiring diagram.
© 2012 Rick Muscoplat
Posted on by Rick Muscoplat