Got a third brake light but others dont work - 2004 Ford F250

Third brake light is on a differnt wrie then the turn signals on the truck. This is so it doesn't blink like your turn/brake lights do. Your fuse panel in the truck houses the fuses for the brake and turns on the truck .The fuse panel in the engine compartment houses the fuses for the trailer brake and turn. Check your fuses in the panel below your steering column for blown fuses and also check your rear bulbs as i have seen both burnt out at the same time. otherwise check your wiring harness right behind the last crossmember on the left side up by the spare tire. Sometimes they get corroded there at the connections.