* Worn-out window regulator: This is the most common culprit. The regulator is the mechanism that raises and lowers the window. Over time, the plastic parts can wear, break, or become misaligned, causing the window to fall.
* Broken window regulator motor: The motor powers the regulator. A faulty motor can fail to provide enough power to hold the window up, or it might be intermittently working.
* Faulty switch: While less common than regulator issues, a bad window switch can cause erratic behavior or prevent the window from staying up.
* Loose or disconnected linkage: The regulator uses a linkage system to connect the motor to the window. Loose or broken parts of this linkage can prevent the window from staying in place.
* Binding window: The window itself might be binding in the channels due to dirt, debris, or damage to the window channels.
How to diagnose and fix:
1. Inspect the Window Channels: Start by carefully inspecting the window channels for any obstructions (dirt, debris). Clean them thoroughly. Lubricate the channels with silicone spray to see if that improves the situation (it might if it's just binding). This is the easiest and cheapest fix to try first.
2. Check the Window Switch: Try the window switch multiple times. If it feels loose, sticky, or unresponsive, it could be faulty and need replacement. Try the switch in different positions (full up, full down) to see if the problem persists.
3. Listen for the Motor: When you try to raise the window, listen carefully for the motor. If you hear a clicking sound but no movement, the motor might be weak or failing. A whirring or grinding sound usually indicates a problem within the regulator mechanism itself.
4. Manual Inspection (Advanced): This requires removing the door panel. Before you do this, disconnect the battery's negative terminal to prevent accidental short circuits.
* Remove the door panel: Consult a repair manual specific to your 1989 Cadillac DeVille for detailed instructions on removing the door panel. It usually involves removing screws, carefully prying off clips, and disconnecting electrical connectors.
* Inspect the Window Regulator: Once the panel is off, you'll have access to the window regulator. Carefully examine it for broken plastic parts, stripped gears, or anything obviously broken.
* Test the Motor (if possible): If you have access to a multimeter, you can test the motor for continuity and proper voltage. This requires some electrical knowledge. If you're not comfortable doing this, skip this step.
Repair Options:
* Replace the entire window regulator: This is the most likely fix. You can find replacement regulators online or at auto parts stores (specify your vehicle's year and model). Replacement involves removing the old regulator and carefully installing the new one.
* Repair the window regulator (if possible): Sometimes, you can repair a broken regulator by replacing individual broken parts. This is only feasible if you can find replacement parts and have mechanical skills.
* Replace the window motor: Less common than regulator issues, a faulty motor requires replacement, which is often integrated with the regulator as a single assembly.
* Replace the window switch: If the switch is faulty, replace it.
Recommendation: If you are not comfortable working on car electrical systems and mechanical components, it is best to take your car to a qualified mechanic. Replacing the window regulator is not a simple job, and incorrectly installing it could cause further damage. A repair manual specific to your car year and model will greatly assist you if you choose to do the repairs yourself.
