power window troubleshooting

[poctai]

I'm trying to figure out how to fix my front passenger window which doesn't work. There's no clicking when I try to use the drivers' door controls. All the other windows work and the front passenger door lock and motorized mirrors work as well. I'm thinking the power window motor in that door doesn't work. I read the how-to on disassembling the door panel, so I can do that. I have read the problem can be a cable being crimped somewhere. Is there a way to figure out what the problem is without taking off the door panel?

Thanks

[brendanpower]

90% of the time, its a window switch or broken wire in the door boot.
P/S window does not work from drivers or passenger switch?
The door panel comes off pretty easy, but the place to start is at the P/S window switch. Using a meter or test light, check that there is power to the switch, and then that the switch is actually working. A wiring diagram would be helpfull, but im not on my work computer.
If you have the door panel off, you can just trace the wires down to the window motor and test them there. Usually a 2 wire harness. One is switched power, one is ground. If the switched power is getting to the motor, then you need a motor. If not, then you need to trace back.

[the roadie]

Trailvoys are not like other older vehicles with a direct connection between the switch and the motor. The switch gives a signal to the door control module. Then the module sends a serial data bus signal to the BCM (body control module) which then decides if it's a message that it's going to pass on to the destination. For instance, if the passenger window switch is pressed by a child or dog, but the driver's door window lockout button was previously pressed, the passenger's window isn't going to move. It's a safety thing.

Plus the windows are allowed to move temporarily after turning the vehicle off but before opening the door. This also takes the smarts of the BCM.

All that being said (for the benefit of the lurkers), your problem not in serial communication since that's also needed for the door locks and mirror control. The harness crimping issue is one of wires being broken after too much flexing, usually inside the rubber boot at the door hinge area. But if the power or serial data lines were broken, you would have more failures than just the window motor.

So we can post or describe the schematic if you own a meter and know how to use it, and want to poke about in the door and measure the switch and motor voltages. Is that what you wanted to go into? I only ask that because I've often launched into long-winded explanations to help people troubleshoot things, only to have them say it was way too complex and all they had was a test lamp (or less) when they needed a meter to do it properly.

[poctai]

I have a meter I borrowed from the office. I've only used it once to test the battery.

[poctai]

Ok, I've learned how to use the meter (Got a Sperrry DM4100A), can someone walk me through the testing procedure?


Thanks

[poctai]

as it turns out, no power is going to the motor. I was actually hoping it was a bad motor, since that's an easier problem to fix.

[the roadie]

Do you have 12V on the Orange wire going to the switch module? If not, you have a bad wire in the hinge area, or a blown Circuit Breaker #1 in the rear fuse block, but that would also take out the rear window as well.

If you have 12V on the switch module, and the switch doesn't work, then you have a bad module or dirty switch.

[poctai]

Thanks for the info Roadie. I may have to take the door panel off again, I think. Maybe I didn't check the voltage at the motor properly. I say that because I just test the voltage coming off the orange cable (crudely circled in attached picture - picture taken from driver side, I tested both sides to be sure) and it was a clear 12.85 volts. Either, like you say, the actual switch/module went bad or it's still the motor.

[the roadie]

The motor is a traditional bidirectional floating one, meaning both wires to it come from the module. Other motors like blowers or windshield wipers might have one end permanently grounded, and the other input is turned on and off to 12V. (Or one end always at 12V, the the low side gets switched.)

But in a bidirectional motor, the control module controls BOTH inputs, so it can put 12V one way for up, and reversed the other way for down. Same idea for lock/unlock solenoids.

[poctai]

I just tried switching the driver and front passenger door modules and still no joy. I'm really starting to think it may really be the motor after all.