First of all, vehicle circuits are protected by fuses, circuit breakers, and fusible links. The main fuse panel is in the engine compartment, and another is inside the passenger compartment. If an electrical component fails, check the fuse first. Replace blown fuses with the correct type. If a replacement fuse fails, correct the problem before replacing it again. Some circuits use fusible links, which melt if the circuit carries too much current. Replace blown links with the same specification, and troubleshoot the circuit if the replacement link blows.