Auto Repairs how to Test a Fuse
Fuses are installed in cars, trucks, and other vehicles to prevent a surge of current from damaging certain electrical parts. Generally, if a fuse is blown, the functions or features that the fuse was designed to protect will be inoperable. There are several ways to determine whether or not a fuse has blown.
• With a circuit tester
A circuit tester is a small, inexpensive device that can be used to determine whether or not an electrical circuit is good. When used on a fuse, it will test if the fuse is blown (not working) or operational. Depending on what kind of circuit tester is used, its function may vary slightly, but in general a circuit tester will have two leads (sharp metal points) that get connected to either side of the fuse (touching the fuse's metal surface). If the fuse is good, the circuit tester will either emit a beep or light up (or sometimes both). If the fuse is bad, nothing will happen.
A circuit tester can be a handy tool to have, for testing fuses as well as other electrical circuits. An inexpensive, basic model can be purchased for about three bucks from Home Depot and most other hardware stores.
• With a multimeter
Multimeters are very expensive, but if one is available it can be used just like a circuit tester (described above). Set the meter to Logic and touch each of the two leads to the metal on either end of the fuse. If the meter beeps, the fuse is still good.
• By swapping fuses
The fuse boxes in most cars and trucks contain fuses of several different ratings. If there is another fuse that's rated exactly the same as the fuse that is suspected to be bad, remove the known-good fuse (with the vehicle off) and install the suspect fuse in its place. Then turn the car on and see if the component connected to that fuse will operate. If it won't, the fuse is very likely bad; but if it does work, the fuse is definitely good.
When swapping fuses, only do it with fuses that are rated exactly the same as each other and that look identical. Putting the wrong fuse into a slot where it doesn't belong can create new problems, as well as be potentially dangerous. If there are no fuses that are the same as the one suspected to be bad, packs of various fuses can be purchased at most auto parts stores or hardware stores, and even many gas stations.
