Which is the fuse for the interior lighting on a 2003 Ford Expedition?
Fuse number 21, which is a 15A Minifuse. The black fuse cover
should give you a reference as to which fuse is numbered what.
To give you a rough idea of which one it is, if you notice,
under the 6 black relay (the big black cubes, 3 per row) there
should be a line of minifuses. #21 is furthest one on the right, to
the right of a green one.
Hope this helps.