1. Identify the Problem:
* Window won't go up or down at all: This points to a power issue (fuse, switch, wiring, motor) or a mechanical problem (regulator, cable).
* Window goes down but not up (or vice versa): This often indicates a problem with the regulator or motor.
* Window goes up/down intermittently: Could be a loose connection, failing motor, or a problem with the switch.
* Window is slow: Usually points to a worn motor or regulator.
* Window makes grinding noises: This suggests a problem with the regulator or a broken window track.
2. Troubleshooting Steps:
* Check the Fuse: Consult your owner's manual to locate the window fuse and check if it's blown. Replace it if necessary.
* Test the Window Switch: Try the passenger side window switch to operate the driver's side window. If it works, the problem is likely with the driver's side switch. If it doesn't, the problem is elsewhere.
* Inspect the Wiring: Carefully examine the wiring harness leading to the window motor for any breaks, frays, or loose connections. Pay close attention to the area where the harness enters the door.
* Test the Window Motor: This requires some disassembly. You'll need to remove the door panel (plenty of videos online showing how to do this for a 1999 Pontiac Montana) to access the motor. You can often test the motor with a multimeter or by directly applying power (be very cautious when doing this).
* Inspect the Window Regulator: The regulator is the mechanism that moves the window. If the motor is working but the window doesn't move, the regulator is likely the culprit. This often requires replacement.
* Check the Window Tracks: Inspect the tracks for any obstructions or damage. Debris can prevent smooth window operation.
3. Repair Options:
* Replace the Fuse (easiest): This is the simplest and cheapest fix.
* Replace the Switch (moderate): Relatively easy to replace, but requires some disassembly.
* Repair or Replace the Wiring (moderate to difficult): Can be challenging depending on the extent of the damage.
* Replace the Window Motor (moderate to difficult): Requires door panel removal and some mechanical skill.
* Replace the Window Regulator (difficult): This is often the most challenging repair, requiring significant disassembly of the door.
4. Getting Help:
* Online Resources: YouTube videos are invaluable for visualizing the repair process. Search for "1999 Pontiac Montana driver's side window repair."
* Repair Manuals: A repair manual specific to your vehicle will provide detailed instructions and diagrams.
* Auto Parts Store: Staff at auto parts stores can assist with identifying the correct parts.
* Mechanic: If you're not comfortable performing the repair yourself, take your vehicle to a qualified mechanic.
Important Safety Note: Disconnecting the battery's negative terminal before starting any electrical work is crucial to prevent accidental shocks or shorts. Always exercise caution when working with car parts. If you're unsure about any step, it's best to consult a professional.
