* Wiring harness break: The most common culprit after replacing all those components is a break or short in the wiring harness *between* the rear gate and the vehicle's main harness. The harness is vulnerable to flexing and wear where it enters the vehicle body. Carefully inspect this harness for cuts, chafing, or broken wires. Pay close attention to where the harness bends as the rear gate opens and closes.
* Ground fault: A poor ground connection somewhere in the circuit can prevent the motor from working. Check the ground points associated with the rear window motor and its wiring. Clean and secure any corroded ground connections.
* Fuse (less likely): Although you've replaced many components, a blown fuse could still be at play, especially if the issue affects other systems. Check your owner's manual to find the fuse for the rear window and test it.
* Body Control Module (BCM) issue (unlikely but possible): In some vehicles, the BCM controls power to the rear window motor. While less likely after replacing other parts, a malfunctioning BCM could still be preventing power from reaching the motor. This is a more advanced diagnostic requiring specialized tools.
* Incorrect motor installation: Although you stated you replaced the motor, there's a small chance it wasn't installed correctly. Double-check all connections. Ensure the motor is securely mounted and that all gears mesh appropriately.
Troubleshooting Steps:
1. Visual inspection of the wiring harness: This is the most important step. Thoroughly examine the entire harness from the rear gate to the vehicle body. Look for any signs of damage. You may need to carefully trace the wires to find the break.
2. Check grounds: Locate the ground points for the rear window motor and its related wiring. Clean them with a wire brush and reconnect securely.
3. Test for power at the motor: With the switch activated, use a multimeter to check for power at the motor's connection points. If no power is present, start tracing the wiring back towards the switch to locate the break.
4. Check fuses: This is a quick and easy check.
If you've carefully checked all of the above and still have no luck, it might be time to consult a qualified auto electrician. They have the tools and experience to diagnose more complex electrical problems.
