* Wiring Harness: Check the wiring harness carefully between the switch, the regulator, and the motor. Look for broken wires, corrosion, or loose connections. A visual inspection might not be enough; you might need a multimeter to test for continuity and voltage at various points in the harness.
* Switch Failure (despite having power): Even though you have power reaching the motor, the switch itself might be faulty. It might be sending an intermittent or weak signal, or it might have an internal short that prevents proper operation. Try testing the switch's output with a multimeter.
* Poor Ground: A bad ground connection can prevent the motor from operating correctly. Ensure the regulator and motor have a good, clean ground connection to the car's chassis.
* Broken Regulator Gear: Even with a new regulator, the internal gear mechanism could be stripped or broken preventing the window from moving. This is less likely if you've already replaced the regulator, but worth considering if you used a used part.
* Window Binding: Check if the window itself is binding or obstructed. Something might be preventing the glass from moving smoothly. Try lubricating the window tracks with silicone-based lubricant.
Troubleshooting Steps:
1. Visual Inspection: Carefully examine all wiring, connections, and the window mechanism for any obvious damage.
2. Multimeter Test: Use a multimeter to:
* Check for power at the switch: Should be 12V when the switch is activated.
* Check for power at the motor: Should be 12V when the switch is activated. You already said you have power here, but double-check.
* Check continuity in the wiring harness: Ensure there is no break in the wiring between the switch, regulator, and motor.
* Check the ground connection: Ensure a good ground connection between the regulator/motor and the chassis.
3. Switch Test (Advanced): If you suspect the switch, you might need to bypass it directly with power to confirm if it's the issue. Caution: This should be done carefully to avoid short circuits.
4. Window Lubrication: Lubricate the window tracks and ensure nothing is binding the window.
5. Manually Operate the Window (if possible): If you can carefully access the window regulator mechanism, try manually lifting the window to see if it is free to move. This will help determine if the problem is in the motor, the regulator, or the window itself.
If you've gone through these steps and still can't identify the problem, it's best to consult a qualified auto mechanic. They have the tools and expertise to diagnose the issue more accurately.
