The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired.
Fuses are color-coded with standardized color identification and ratings. For service replacement, non-color fuses of the same respective rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown.
The Autofuse, normally referred to simply as "fuse" is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components.
The MaxiFuse was designed to replace the fusible link and Pacific Fuse elements. The MaxiFuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the MaxiFuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the MaxiFuse was designed to be a slower blowing fuse, with less chance of nuisance blows.
The MiniFuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the MiniFuse is usually used to protect the wiring assembly between a fuse block and system components. Since the MiniFuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses.
PACIFIC FUSE ELEMENT/MAXIFUSE
The Pacific Fuse Element and MaxiFuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in future vehicle applications.
Your vehicle likely has several fuse box locations. There may be one or two underhood electrical centers with fuses and relays. There could also be an underdash fuse box. Some models have removable end caps on the instrument panel harboring a fuse box. Always consult your Owner's Manual for fuse box location specific to your vehicle.
- Remove the trim panels or covers necessary for access to the fuses.
- Locate the fuse for the circuit in question.
- Check the fuse by pulling it from the fuse box and observing the element. If it is broken, install a replacement fuse of the same amperage rating. If the fuse blows again, check the circuit for a short to ground or faulty device in the circuit protected by the fuse.
- Continuity can also be checked with the fuse installed in the fuse box with the use of a test light connected across the two test points on the end of the fuse. If the test light lights, replace the fuse. Check the circuit for a short to ground or faulty device in the circuit protected by the fuse.