* Driver's Side Master Switch: This is the most common cause. The master switch itself is faulty. While it can control all the windows, it's a complex assembly and a single internal component failure can prevent the other window switches from working. This switch often needs replacement rather than repair.
* Wiring/Connectors: A break or poor connection in the wiring harness leading from the driver's side master switch to the other switches, or to the window motors themselves, could be the issue. Look for frayed or corroded wires, particularly near the door jambs where the wiring flexes frequently. Check connectors for proper seating and corrosion.
* Body Control Module (BCM): The BCM acts as the central control unit for many electrical functions, including power windows. While less likely, a malfunctioning BCM could be causing the problem. This is usually diagnosed with a scan tool by a mechanic.
* Passenger Side Switches (Less Likely): While the problem is most likely in the driver's side master switch or wiring, it's possible that the individual passenger-side switches have failed, but this would be less common than a master switch issue.
Troubleshooting Steps:
1. Check Fuses: Begin by checking the fuses related to the power windows in the fuse box (usually under the hood or the dash). Your owner's manual will show the fuse locations and ratings.
2. Test the Passenger Switches: Try the passenger-side switches. If they don't work at all, then the problem likely lies in the wiring or the BCM. If they work intermittently, it could still point to a wiring issue.
3. Inspect Wiring: Carefully inspect the wiring harness leading from the driver's side switch to the passenger-side switches and window motors. Look for broken or frayed wires, especially at the points where the wires pass through the door rubber seals.
4. Test the Driver's Side Master Switch: If you have a multimeter, you can test the continuity of the switches within the master switch assembly. However, this requires some electrical knowledge and is often best left to a qualified mechanic. You could also try swapping the master switch with one from a junkyard vehicle to test if the switch itself is at fault.
If you're not comfortable working with car electrical systems, it's best to take your Pontiac Montana to a qualified mechanic for diagnosis and repair. Replacing the driver's side master switch is a relatively common repair, but tracing wiring issues can be time-consuming.
