What could be wrong with brake lights if not the switch bulbs or fuses?

Answer 1

Sounds like you've been doing some guessing! You need to find where the power stops. Use a test light at the sockets. If no power, go to the wire to the socket. When you find where power goes in but doesn't come out, you have your answer. Assuming there is one answer. There is also a possibility of a ground problem. Good luck. If it uses the same bulbs for brake lights and rear turn signal lights, it's possible that the turn signal switch is faulty. On these designs, the brake light circuit runs through the turn signal switch so that when you turn, the brake light for that side is disconnected, allowing the bulb on that side to blink (otherwise the bulb would stay on steady for the brake light function).