I realize this is an old post but this is the same problem I am having with my 93 Civic DX. Mine is not intermittent though, I have no horn or brake lights. I checked the fuse, brake switch, and the actual bulbs themselves and all appear good. I have not checked the horn switch, but I don't believe the two are interconnected once they leave the fusebox. I have power at both sides of the fuse. Anyone run into this problem before?