The electrical circuits of the vehicle, thus, are protected by fuses, circuit breakers, and fusible links; the principal fuse/relay enclosure is in the engine compartment, while the interior fuse/relay enclosure is in the passenger compartment. Available in small, medium and large sizes, the fuses have the same blade terminal configuration, with large and medium fuses removed by hand and the small sizes requiring the use of pliers or a small plastic fuse-puller. When an electrical component fails one must check the fuse, and after removing the outer layer of shrink and using the test light to put the tip on the exposed terminals, one may see the fuse is blown, a sign of a melted element. When one of the fuses has been blown, it is important to use correct kind of fuses as the physical appearance of the fuses which should restrict current can be very similar, but the amperage of the fuses shall differ. Should a substitute fuse blow soon after replacement, then the cause is usually a short circuit by virtue of a faulty wire, and this should be fixed. In addition, some circuits are protected by fusable links, which are applied to high-current load circuits and are made to melt under excessive current. If it is required to replace a particular fusible link that has been blown, it is recommended that a similar type of link be used and, if the new link also fails, then it should be traced in the circuit.
