1. Window Regulator:
* Broken Cable: The most common cause. The cable inside the regulator mechanism may be broken, frayed, or detached. This prevents the window from moving down.
* Worn or Stripped Gears: The gears within the regulator can wear down over time, especially if the window has been forced or jammed. This will prevent smooth up and down movement.
* Regulator Assembly Failure: The entire regulator may be faulty.
2. Window Motor:
* Motor Failure: The motor itself could be burned out or failing. It might be able to pull the window up (sometimes with more effort), but lack the power to lower it.
3. Wiring and Electrical:
* Broken Wire: A wire in the harness leading to the motor or regulator could be broken, damaged, or disconnected. This is more likely if the problem suddenly appeared.
* Fuse: Check the fuse for the power windows. It's unlikely the fuse would cause an up-only problem, but it's a quick check.
* Switch: While less likely (as the window goes up), the power window switch itself could be partially malfunctioning. Try the switch several times and see if there's any change in behavior.
Troubleshooting Steps:
1. Check the Fuse: Locate the fuse box (usually under the hood or dashboard) and check the fuse related to the power windows. Replace if blown.
2. Listen Carefully: When you try to lower the window, listen closely for any unusual sounds (grinding, clicking, buzzing) from the door. This can help pinpoint the problem area (regulator, motor).
3. Manual Check (if possible): If you can access the regulator mechanism (usually requires removing the door panel), you can manually try to move the window up and down. This will help determine if the regulator itself is at fault.
4. Test the Window Switch: Try the passenger window switches (if they work). If they do, it points away from a switch problem.
5. Check Wiring (Advanced): This requires removing the door panel and carefully inspecting the wires leading to the motor and regulator. Look for any breaks, frays, or loose connections.
What to Do:
* If you're comfortable working on cars: You can try replacing the regulator or motor yourself. Repair manuals and videos are available online. This is often the most cost-effective solution.
* If you're not comfortable working on cars: Take your Impala to a qualified mechanic. They can diagnose the problem and perform the necessary repairs.
The most likely culprit is a faulty window regulator. The fact that the window goes up suggests the motor and some parts of the regulator still function, but a broken cable or worn gears are preventing the downward motion.
