The weakest link in an electrical chain is the fuse. That’s by design. If a circuit gets too much power, you want the fuse to blow rather than the radio, computer, or other gadget. That make’s sense. Also it makes sense to first check the car’s fuse system when something electrical that should work quits.
A fuse is an electrical component that’s designed to fail first before an electrical overload damages other, more expensive, components. A fuse box (or fuse panel) is a group of fuses placed in a relatively convenient location.
How and where can you check and replace car fuses? The hard part may be finding them. Fortunately, most modern cars put all fuses together in one, two, or (probably) both spots:
- Under the hood near the battery (battery, headlight, stoplight, hazard light, horn, heater, air conditioner, and other fuses and relays)
- Inside the car under the dashboard (wiper, coil, turn lights, washer, mirrors, fuel pump)
To quickly test fuses, buy a test light (available from auto parts stores), hook the light to a nearby ground connection (see the light’s instructions), turn the car’s ignition to on and touch the light’s probe to the fuse. If the tester lights up (continuity), the fuse is good. Using this method, you can quickly test many fuses without removing them.
Before you go out and buy extra fuses for emergencies, check the fuse box(es) to see what’s already there. Many modern cars include a small assortment of spare fuses and maybe even a special tool called a fuse puller. However, you may want to get an extra relay or two as they are cheaper now than when needed 50-miles from a parts store.
How can you check and replace car fuses? In most cases, visually. Many fuses are translucent and you can see through the plastic or glass case to determine if there is a break in the fuse. Alternately, you can use a volt-ohmmeter (VOM or multimeter) to check for continuity. VOMs are less than $25 at auto parts or electronics stores and are handy for testing lots of electrical things. Instructions typically come with the unit.
Testing continuity means testing the resistance between the two ends or prongs of the fuse. The VOM actually sends a small electric charge (from an internal battery) through the fuse and measures whether it comes out the other end. If not, the fuse is blown and must be replaced.
Caution: remember that you are working with electrical current and be respectful of its power.