Much like the electrical system in your house, your car has a fuse box that helps protect against certain types of electrical mishaps. If you're having an issue with an electrical component in your vehicle, knowing how to replace a fuse in your car could be the key to getting things running again.
It helps to know exactly what a fuse does and how it works. Electrical systems can be somewhat unstable, prone to things like short circuits, surges and power overloads. If one of these events were to happen in a car, it could damage important circuits that would then be quite difficult to fix. Fuses are designed to act as a bridge for the major electrical systems in the vehicle, to prevent damage to the car's electrical components.
This is why many of the common electrical issues in both homes and cars can be fixed by going to the fuse box. Essentially, all of the electric energy needs to pass through the fuse. Yet the fuse is designed to break if the voltage gets too high for the circuit to handle. This kills the circuit and prevents it from becoming overloaded and doing major damage to the car or home. When this "bridge" stops working, the electrical component it is tied to will stop working as well - but at least you'll only need to replace the fuse, rather than the entire circuit.
Armed with this knowledge, it becomes simple to see why your dashboard light stopped working, or the radio suddenly lost power - it's probably due to damage for that particular component's fuse. Fortunately, replacing a blown fuse is designed to be quite simple. There are two main locations for the fuse box on a car - either under the hood or by the driver's left knee under the dashboard, hidden by a panel. Use your owner's manual to locate the fuse box on your own car, then open it up.
To make things even easier, the cover to the fuse box typically contains a chart that lists which fuses control each aspect of the vehicle. The fuses are typically brightly colored and may have different numbers on them - this is the amperage that the fuse uses. There are two ways to test a fuse - visual inspection, or using a test light. A test light is very simple to use in that touching it to any fuse should immediately show whether the fuse is working or not. Visual inspection requires removing the fuse using the removal tool included in every fuse box (you can likely use your fingers as well). If the fuse looks damaged or "burned out," it needs replacing.
Take the blown fuse down to your local auto parts store, where you should be able to find an exact match of the correct amperage. Be sure not to buy a replacement with anything other than an equal amperage or you'll simply cause yourself more problems. Fuses are typically quite cheap, and you might want to consider buying a pack of various amperages while you're there, as these will likely come in handy if you have another electrical issue.
Simply pop the new fuse into the slot where the old one was and your part should come back to life. In some rare cases, the new fuse may blow immediately after installing it. This typically means you have a larger electrical problem that should be left to a professional.