The electrical circuits of the vehicle are protected by fuses, Circuit Breakers or Fusible links The Main fuse/relay assembly is located in the engine compartment while the interior fuse/relay is in the passenger compartment. Small, medium and large fuses that are used in the fuse blocks are of the same blade terminal type; while medium and large fuses are inserted/withdrawn manually, small fuses need to be withdrawn using pliers or a small plastic fuse-puller tool. When there is a problem with the electrics on a car, the starting point must always be the fuse check, and for this there is no better tool than a test light to probe the exposed opened ends of a fuse; if power is present on one side and not the other then the fuse is blown, this can also be seen. When replacing fuses it is important that only correct types are fitted as there may be fuses of different ratings that are interchangeable in that they appear identical but only the correct rating should be used and in most applications the appropriate amperage rating will be molded into the top of the fuse case. If a replacement fuse goes out right away, then it should not be replaced, it should be figured out why it has gone out again usually due to a short in a wire. Furthermore, some circuits have fusible links, where in a circuit that is not normally fused or has a high current such as in connections between alternator and battery, they are made of a material that melts as current increases and need to be replaced by one with the same specifications; if it blows out again, it is time to investigate the circuit before placing a new link.