The brake light fuse in a 2002 Ford Mustang is
not a single fuse. The brake lights are typically controlled by more than one fuse, and sometimes a relay as well, depending on if there are other circuits sharing the power. To find the correct fuse(s), you
must consult your owner's manual.
The owner's manual will have a fuse box diagram showing which fuse(s) are responsible for the brake lights. Without that diagram, any answer here could be wrong and potentially lead to further electrical problems.