Here's a breakdown of the troubleshooting and repair process:
1. Identify the Problem:
* Does the window motor make any noise? If you hear a clicking sound, it might be a faulty motor or a bad connection. No sound suggests a power, switch, or regulator problem.
* Does the window move at all? Even a slight movement indicates the motor is working, and the problem lies elsewhere (regulator, switch, or wiring).
* Does the window bind or feel stiff? This points towards a problem with the window regulator mechanism. Rust and wear are common culprits in older cars.
* Is the window switch working properly? Try other window switches to see if the problem is isolated to the left rear switch or a more general electrical fault.
2. Troubleshooting Steps:
* Check the Fuse: Consult your owner's manual to locate the fuse for the power windows. Replace it if blown.
* Inspect the Wiring: Trace the wiring harness from the switch to the motor. Look for broken wires, corrosion, or loose connections. Pay close attention to the areas where the wiring harness passes through the door rubber seals – these areas are prone to wear and tear.
* Test the Window Switch: Use a multimeter to check for continuity between the switch terminals when activated. A faulty switch will need replacement.
* Test the Window Motor: With the switch disconnected, connect the motor directly to the battery (using appropriate gauge wires) for a brief test. If the motor runs, the issue is elsewhere (switch, regulator, or wiring). If not, the motor needs replacement.
* Check the Window Regulator: This is the most complex component. It's responsible for raising and lowering the window. Access to it requires removing the door panel. Common problems include broken cables, worn gears, or seized mechanisms. You might need to replace the entire regulator assembly.
3. Repair/Replacement:
* Window Switch: Relatively inexpensive and straightforward to replace. You'll likely need to remove the door panel to access it.
* Window Motor: Can be expensive. Replacing it involves removing the door panel and disconnecting the old motor.
* Window Regulator: This is the most challenging repair. It often requires removing the door panel, detaching the window glass, and disassembling the regulator to repair or replace damaged components. This is usually a job best suited for someone comfortable with auto repair or a professional.
* Wiring: Repairing broken or corroded wires can be time-consuming, requiring careful tracing and splicing.
4. Resources:
* Mercedes-Benz Repair Manuals: A factory service manual will provide detailed diagrams and instructions.
* Online Forums and Communities: Search online forums dedicated to Mercedes-Benz 190E owners. You may find others who have tackled the same repair and can offer advice or troubleshooting steps.
* Auto Parts Stores: Check your local auto parts store for replacement parts. Be sure to specify the year and model of your vehicle.
Important Considerations:
* Door Panel Removal: Removing the door panel can be tricky and may require specialized tools. Numerous online videos and guides demonstrate this process for the 190E.
* Window Glass Handling: Be extremely careful when handling the window glass to avoid breakage or injury.
* Professional Help: If you're not comfortable working on car electronics or mechanics, consider taking your car to a qualified mechanic specializing in Mercedes-Benz vehicles.
This detailed guide provides a comprehensive approach. The actual repair will depend on the specific cause of the malfunction. Remember to always prioritize safety and proceed methodically.
