First, check fuse 43. Your owner's manual should show the fuse box location (usually under the hood or in the passenger compartment, often near the steering column). Locate fuse 43 and carefully inspect it. Look for a blown filament (a broken wire inside the fuse) – it will look dark or broken. If it's blown, replace it with a fuse of the same amperage rating (the number printed on the fuse).
If fuse 43 is NOT blown:
The problem is likely more complex than a simple blown fuse. The possibilities include:
* Window motor failure: The motor itself may have failed. This requires replacement.
* Window regulator failure: The regulator is the mechanism that moves the window up and down. A broken regulator is common and requires replacement.
* Wiring problem: A wire may be damaged, loose, or disconnected somewhere between the switch, the motor, and the fuse. This is more difficult to diagnose and repair, often requiring tracing the wiring harness.
* Window switch failure: The switch itself could be defective.
Finding your Fuse Box: If you can't locate the fuse box based on your owner's manual, search online for "2004 Ford Mustang fuse box diagram" — many websites have diagrams showing the fuse box locations and layouts. You'll probably find several high-quality images.
Important Safety Note: Before working on your car's electrical system, always disconnect the negative (-) battery terminal to prevent accidental short circuits.
Since you've already checked fuse 43 and it's not blown, you'll likely need to take your Mustang to a qualified mechanic or auto electrician for diagnosis and repair. They have the tools and expertise to pinpoint the exact problem. Trying to troubleshoot electrical problems without the proper knowledge can be risky and potentially damage other components.
