my BMW 3 Series E90/E91 (2005-2012) windows won’t go down, what should I check?

Solution

1. Preparation

• Gather necessary tools and materials.
• Disconnect the vehicle battery to ensure safety while working on electrical components.

2. Inspect the Fuse

• Locate the fuse box, typically found under the dashboard or in the engine compartment.
• Remove the cover and identify the fuse for the window system (refer to owner's manual).
• Use a fuse puller or pliers to remove the fuse and visually inspect for damage.
• Replace with a new fuse of the same amperage if blown.

3. Check the Switches

• Remove the door panel using a socket set and trim removal tools.
• Disconnect the window switch assembly from the harness.
• Inspect for signs of corrosion or damage; clean contacts if necessary.
• Test switches with a multimeter to check for continuity.

4. Inspect Wiring and Connectors

• Visually inspect the wiring harness leading to the window motors.
• Look for any frayed wires, broken connectors, or signs of wear.
• Repair or replace any damaged sections of the wiring as needed.

5. Test Window Motors

• Remove the window motor from the door panel.
• Connect the motor to a suitable 12V power source (ensure proper polarity).
• Observe if the motor operates; if not, replace the motor.

6. Reassemble and Test

• Reinstall the window motor and door panel.
• Reconnect the vehicle battery.
• Test the window operation using the control switch.