* Motor: The most likely culprit is a faulty window motor. Over time, they can wear out or seize up.
* Switch: A malfunctioning window switch can send incorrect signals to the motor, preventing full operation.
* Relay: Relays are less likely to be the sole cause of this problem, but a bad relay *could* prevent power from reaching the motor.
* Wiring: Damaged or corroded wiring between the switch, relay (if applicable), and the motor is a common problem, especially in older vehicles. Check for broken wires, loose connections, or corrosion, particularly in the areas where the wiring harness is flexed.
* Window Regulator: The regulator is the mechanism that guides the window up and down. If it's broken or jammed, the window won't move properly. This is a fairly common failure point on convertibles.
* Power: Check the main power supply to the window system. A blown fuse or a problem in the car's electrical system could be at fault.
Troubleshooting Steps:
1. Check the fuse: Consult your owner's manual to locate the fuse for the power windows. Replace it if it's blown.
2. Inspect the wiring: Carefully examine the wiring harness leading to the rear window motor for any damage or corrosion.
3. Test the switch: Try the switch repeatedly. If it feels loose or unresponsive, it may be faulty. You could try swapping it with a front window switch (if they are the same type) to see if the problem moves.
4. Listen for the motor: When you operate the switch, can you hear the motor trying to work? If you hear a clicking sound but no movement, it could be a motor issue or a regulator problem. No sound at all points to a power issue or a more significant electrical problem.
5. Visual Inspection of the Regulator: If possible, try to visually inspect the window regulator mechanism (this often requires removing some interior trim). Look for any signs of breakage or binding.
It's highly recommended to have a qualified mechanic diagnose the problem. While you can try these steps, pinpointing the exact cause without proper tools and experience can be difficult and may lead to unnecessary part replacements. A mechanic can properly test the motor, wiring, and other components to determine the source of the malfunction.
