Power windows are a convenient feature in your GMC, and if you find that they are not working, you'll want to figure out why and get them fixed.
Your power windows can be built on one of three different systems, but the scissor system is the most common. Before you start to take anything apart, check the fuses for the problem. A power window motor cannot operate if the fuse is blown. If you have circuit breakers, check them as well.
- Turn the key to the ON position and check for power to the motor. If you have power, then take the door panel off. Before you change a motor, you need to make sure that it really is the problem.
- While you have the door panel removed and your window switch plugged in, check the motor’s voltage. The plus probe is connected to one of the motor wires, and the negative probe is connected to the other wire. Depress the switch in both positions and look for a reading between 0 and 11 volts. This would indicate that there is a problem in the wiring or the switches and not the motor. If you see 12 volts on the motor, then the motor is bad.
- Before you get a new motor, make sure there is nothing obstructing the motor that would prevent it from working. There could be a broken regulator that may be the problem.
- After you have determined that the problem lies within the motor, take it out and replace it. You may need to remove the regulator first before you can get to the motor.
- Secure the window in a position that will keep it from falling. You can use a stick or masking tape to keep it in place.
- The regulator is more than likely held in place by 1/4-inch rivets that you will need to punch out with a center punch and a hammer. Take the last rivet out by using a ¼-inch drill and holding it in place with pliers.
- After you have removed the rivets, take the regulator arms out of the channels. You can then take the regulator out through the door.
- The regulator has a large clockspring in it, and it can deliver 40 pounds of force, so take precautions to ensure that you do not get hurt when you remove the motor. Once you take the motor off, there can be arms going one way and the chassis going the other. You have to lock the arm to the chassis to keep this from unloading.
- You can clamp the motor and regulator in a bench vise. In a clear and flat spot, drill a ¼-inch hole through the gear and chassis. Put a ¼-inch bolt into the hole and tighten it by hand. This will hold it together.
- The motor is held in place by three 3/16-inch rivets that need to be drilled off with a drill. Once you have the heads drilled off, you can remove the motor. Remove any leftover rivets before you put the new motor on.
- Place a small amount of grease on the gear before you install the new motor. Make sure that all the mounting holes line up before you attach it. You can either rivet it or bolt it back into place.
- Next, remove the ¼-inch bolt that is holding the chassis and the gear together.
- Place the assembly back into the door and line the plastic slides up with the channels. Put a little grease on the channels to help the window slide.
- You can use either rivets or ¼-inch bolts to put the assembly back into place.
- Put the liner and door panel back in place.
- Test your window.
You should have a power window that works just as GMC designed it to, but if you have a problem or this does not solve your window issue, then you may need to consult with a professional technician at your local GMC dealership.