By fuse 15, I mean the number 15 fuse. It is a 10A fuse located on the second row, fourth fuse from the left (not counting the spare fuse) in the under-dash fusebox. The two slots to the right of it should be empty unless you have a Canadian model equipped with daytime running lights. The IG fuses are for ignition/battery related circuits. The car wouldn't run if those were blown.

I would start with the brake switch since it would be easy to check and it would make sense that if the switch weren't functioning properly, it wouldn't come out of park.