1. Fuse:
* Check your owner's manual: Locate the fuse diagram for the power windows. The fuse may be labeled "Power Windows," "Windows," or something similar. It might be a separate fuse for each window or a single fuse for all windows.
* Check the fuse: Carefully remove the fuse and inspect it. Look for a blown filament (a broken wire inside the fuse). Replace with a fuse of the same amperage if blown.
2. Window Switch:
* Test the switch: Try the other window switches. If they work, the problem likely isn't a general power issue. If *none* of the window switches work, the problem is likely the master switch or a more significant electrical problem.
* Check the switch itself: Sometimes, the switch itself can malfunction. Try pressing it firmly and repeatedly. If you have a multimeter, you might be able to test the continuity of the switch (but this is more advanced). If you suspect the switch, replacing it is often the easiest solution.
3. Window Motor:
* Listen for the motor: When you press the switch, do you hear any clicking or whirring from the window motor? If not, the motor might be burnt out or seized. This requires more complex repair or replacement.
* Manual check (if possible): If you can access the motor (usually requires removing the door panel), try to manually move the window regulator to see if it's seized.
4. Wiring:
* Check for broken or damaged wires: This can be tricky. You'll likely need to remove the door panel to inspect the wiring harness going to the window motor. Look for broken wires, frayed insulation, or loose connections. This often occurs where the wiring flexes as the door opens and closes.
5. Window Regulator:
* The regulator: This is the mechanism that moves the window. It can become damaged, especially the cables that wind around the spool. Again, you'll need to remove the door panel to inspect it. A broken cable or bent spool is a common cause of failure.
6. Ground Connection:
* Poor ground: A bad ground connection can disrupt the electrical flow. Check for corrosion on the ground wires and connections within the door.
Troubleshooting Steps:
1. Start with the fuse. This is the easiest and cheapest check.
2. Test the switch. Does it control other windows?
3. Listen for the motor.
4. Inspect the wiring (most likely requires door panel removal).
5. Consider the window regulator (requires door panel removal).
If you're not comfortable working on car electrical systems, it's best to take your Grand Marquis to a qualified mechanic. Replacing the window motor or regulator often requires specialized tools and knowledge. Improper repair could worsen the problem. Remember to disconnect the battery negative terminal before working on any electrical components.
