* Window Regulator: This is the most common cause. The motor itself might be fine, but the mechanism that actually raises and lowers the window (the regulator) is likely failing. The up function often fails first because it's working against gravity. A broken cable or gear inside the regulator is a strong possibility.
* Window Motor: While less likely than the regulator, the motor itself could be weak or failing. It might have enough power to lower the window (assisted by gravity), but not enough to raise it.
* Wiring/Connector: A broken or corroded wire in the harness leading to the window motor or regulator is possible. This is more likely if the problem appeared suddenly after some event (like hitting a bump). Check the wiring carefully for breaks or loose connections, paying particular attention to the connectors at the door.
* Switch (Master or Passenger): Although less probable given you've said it happens with *both* switches, a faulty switch *could* still be the problem. A problem with the master switch is more likely to affect all windows, though. A partially failed passenger switch could act oddly.
Troubleshooting Steps:
1. Check the fuses: Start with the simplest check. Consult your owner's manual to find the fuse for the power windows.
2. Inspect the wiring: Carefully examine the wiring harness running from the door to the body of the vehicle, particularly near the hinges and rubber seals where wires are often damaged by flexing. Look for broken wires, loose connections, or corrosion.
3. Manually test the window: Try to manually raise the window (carefully!). If it's stiff or completely immobile, it strongly suggests a regulator problem.
4. Test the passenger switch independently: If possible, try bypassing the master switch. If the window still won't go up with the passenger switch only, that isolates the issue.
5. Listen for Motor Noise: When trying to raise the window, listen closely at the door. If you hear a clicking sound or a faint whirring, the motor is likely trying to function, indicating a regulator problem. If there's no noise at all, the motor itself might be the issue.
Repair Options:
* Replacement Regulator: This is the most likely repair. You can find replacement window regulators relatively inexpensively online or at auto parts stores. Replacing it yourself is possible but can be challenging depending on your mechanical skills.
* Replacement Motor: If the motor is faulty, replacement is also possible, but less likely than a regulator problem.
* Wiring Repair: If you find a broken wire, splicing in a new section or replacing the damaged harness segment is necessary.
If you're not comfortable working on car repairs yourself, taking it to a mechanic is the safest option. Explain the symptoms clearly and they can diagnose the problem more accurately.
