What fuse controls the exterior lights on a trailer E350?

There isn't a single fuse that universally controls *all* exterior lights on a Ford E350 trailer. The fuse setup varies depending on the year, model, and specific options installed on the vehicle. Exterior lights are often split across multiple fuses, potentially even including some in the trailer's own wiring harness if it's a large setup.

To find the correct fuse(s):

1. Consult your owner's manual: This is the most reliable source. It should have a fuse box diagram showing which fuse controls which circuit. Look for fuses labeled "taillights," "turn signals," "brake lights," "running lights," etc. Some might be combined, others separate.

2. Locate the fuse boxes: The E350 typically has multiple fuse boxes: one under the hood and at least one inside the passenger compartment (often under the dashboard).

3. Check the fuse box diagrams: Each fuse box cover usually has a diagram showing the fuse layout and what each fuse controls.

4. Test the fuses: Use a test light or multimeter to verify whether a fuse is blown. Don't just rely on visual inspection; a blown fuse can sometimes look intact.

5. Check the trailer's wiring: If the problem persists after checking the truck's fuses, the issue might be in the trailer's wiring or a blown fuse within the trailer itself (if it has its own fuse box).

In short: You need to consult your vehicle's owner's manual for the definitive answer. There's no generic answer applicable to all E350s.