Fuses, fusible links and circuit breakers — general information
Fuses
1. The electrical circuits of the vehicle are protected by a combination of fuses, circuit breakers and fusible links. The main fuse/ relay panel is in the engine compartment (see illustration), while the interior fuse/relay panel is located inside the passenger compartment (see illustrations). Each of the fuses is designed to protect a specific circuit, and the various circuits are identified on the fuse panel itself.
i. 1a The interior fuse box is located at the left (driver’s) side of the instrument panel, under a cover just above the diagnostic port
i. 1 b the engine compartment fuse/relay box is located at the left side of the engine compartment
i. 1c the number 2 fuse/relay box is on the right-hand side of the engine compartment
i. 1d the relay block number 5 is behind this access panel
i. 1e There are some fuse circuits on the relay block number 5 as well
2. Several sizes of fuses are employed in the fuse blocks. There are small, medium and large sizes of the same design, all with the same blade terminal design. The medium and large fuses can be removed with your fingers, but the small fuses require the use of pliers or the small plastic fuse-puller tool found in most fuse boxes.
3. If an electrical component fails, always check the fuse first. The best way to check the fuses is with a test light. Check for power at the exposed terminal tips of each fuse. If power is present at one side of the fuse but not the other, the fuse is blown. A blown fuse can also be identified by visually inspecting it (see illustration).
i. 3 When a fuse blows, the element between the terminal’s melts
4. Be sure to replace blown fuses with the correct type. Fuses (of the same physical size) of different ratings may be physically interchangeable, but only fuses of the proper rating should be used. Replacing a fuse with one of a higher or lower value than specified is not recommended. Each electrical circuit needs a specific amount of protection. The amperage value of each fuse is molded into the top of the fuse body.
5. If the replacement fuse immediately fails, don’t replace it again until the cause of the problem is isolated and corrected. In most cases, this will be a short circuit in the wiring caused by a broken or deteriorated wire.
Fusible links
6. Some circuits are protected by fusible links. The links are used in circuits which are not ordinarily fused, such as the ignition circuit, or which carry high current.
7. Cartridge type fusible links are located in the engine compartment fuse/relay box and are similar to large fuses. After disconnecting the negative battery cable, simply unplug and replace a fusible link of the same amperage.
Circuit breakers
8. Circuit breakers protect certain circuits, such as the power windows or heated seats. Depending on the vehicle’s accessories, there may be one or two circuit breakers, located in the fuse/relay box in the engine compartment.
9. Because the circuit breakers reset automatically, an electrical overload in a circuit breaker-protected system will cause the circuit to fail momentarily, then come back on. If the circuit does not come back on, check it immediately.
10. For a basic check, pull the circuit breaker up out of its socket on the fuse panel, but just far enough to probe with a voltmeter. The breaker should still contact the sockets. With the voltmeter negative lead on a good chassis ground, touch each end prong of the circuit breaker with the positive meter probe. There should be battery voltage at each end. If there is battery voltage only at one end, the circuit breaker must be replaced.
11. Some circuit breakers must be reset manually.