Rear window won't go up

SOURCE: Rear windows on 2003 Montana won't close, now

If the lockout switch on drivers door is "OFF"... Window fuse's and relay's may be up under passenger side dash or behind glove box.
Could also be a broken wire in the rubber boot going from the door to the body. You will have to eliminate each till you find the culprit.
The motor and the relay are the most likely to cause this problem. Try swapping the relay with a working window relay. If it still doesn't work, remove the door panel and remove the window motor.
Turn the motor shaft in both directions by hand several turns. Then plug the motor in and see if the switch will now run the motor. Sometimes thats all it takes to get it working again. I have had to do this with brand new motors. If voltage is not present at the motor connector, either a bad switch or a broken wire exsists. Make sure to check for voltage coming to that windows switch. Actually, GM use's a circuit breaker type relay for each window and one fuse for all the circuit breakers.