The wire that runs up the piller to the roof lights could be shorted. that wire plugs in seperately into the headlight switch. disconnect it fron the switch and try it, Also the fuse block sometimes has extra lights pluged into the lamps aux port, try the same there. And one other problem area is under the carpet by the sill plate, pull the plate and look under the carpet. There is also a major splice/junction in the main harness behind the inst. cluster, the factory used some duct type tape to cover the splice that could have come off.