Which is the fuse for interior lighting on a 2003 Ford Expedition?

The fuse for the interior lights on a 2003 Ford Expedition isn't a single, easily identified fuse. The lighting system is often spread across multiple fuses, depending on which lights are malfunctioning (dome, map, cargo, etc.).

To find the correct fuse(s), you must consult your owner's manual. The manual will have a fuse box diagram showing the location of the fuse boxes (there's usually one under the hood and one inside the vehicle, often in the glove box or under the dash) and a legend detailing which fuse controls what circuit. The diagram will clearly indicate which fuse(s) are responsible for the various interior lights.

Without the owner's manual, it's impossible to give you a definitive answer. Trying to guess could lead to further electrical problems.