HOW TO TEST A CAR FUSE? THREE EASY WAYS -

If an appliance like a radio, power window, blower, or else suddenly stops working in your car, the first thing you should do is test a fuse and see if it’s OK.

If you don’t know how, then this article will show you three simple ways to do it.

All of them are easy, and you can do them on your own for sure.

Besides this website, you can also watch videos on our YouTube channel, where we have many car-related videos that may help with maintenance, driving, etc.

WHAT IS A FUSE?

Just a few short words about the fuse and its purpose for viewers who are new to all this.

The fuse is a protective measure for your car’s electrical and electronic installation.

It is essentially two terminals connected by a metal strip. All of this is encapsulated in a non-flammable plastic or, rarely, glass casing.

The strip in the middle is thin on purpose so it can burn out in case of a short circuit or an overload.

When it burns out, the complete electric circuit is cut off and the installation and appliances are protected from further damage or, God forbid, fire.

MAKE A VISUAL INSPECTION

The first and easiest way to test a fuse is to take it out and inspect the metal strip inside.

Every fuse is either transparent or has an opening on top of it, so when you take it out, you can clearly see if the fuse is burnt out or damaged.

So, when an appliance does not work, first find the fuse for it using the car’s fuse diagram.

Pull the fuse out, and look at the strip inside. If it’s intact, the fuse is OK.

But if it’s broken, burnt, or totally evaporated, you have to replace it.

USE A TESTER LIGHT

The next easy way to test a car fuse is to use a tester light. It shows if there is conductivity between the two terminals of the fuse, and is the strip inside intact or not.

When testing, know this: some fuses are under voltage always, some only when the ignition is on, and some only when you turn on the appliance.

The best way to avoid confusion and making a mistake is to first find the matching fuse for the problematic appliance and then test it.

So first, connect the tester clamp to ground, which means a clean metal part of the car body. Best find a place around the fuse box, like a screw, hinge, or else.

Make sure the ground connection is clean and tight to avoid a false reading.

On the fuses, you’ll see either an opening on top of the fuse or two metal contacts on each side. Both are access points for checking the metal strip.

If the fuse has an opening, insert the tip of the tester into the opening. Be gentle so you don’t damage or break the strip. If the tester lights up, the fuse is Ok; no light means the fuse is faulty.

With the two contacts on each side, touch one contact, then the other. If there is a light on both sides, the fuse is Ok. If there is light on only one contact, the fuse is the problem.

USE A MULTIMETER

You can also use a multimeter; the basic principle is the same.

First, set the multimeter to 20 volts DC current (this is for a 12-volt installation).

Next, connect the black probe to ground and use the red probe to touch the fuses.

If the fuse has an opening, touch the strip inside with the probe. If you have a voltage reading, the fuse is OK. No reading means the fuse is burnt out or damaged.

If the fuse has two contacts, touch one contact and then the other. If both contacts give a voltage reading, the fuse is OK. If only one contact gives a reading, the fuse is faulty.

So, it’s basically the same as with the tester light, only this time, you have a voltage reading instead of an LED light.

CONCLUSION

Our recommendation for testing a fuse is to use a tester light. It is the simplest option, and it’s accurate.

But, with both the multimeter and tester light, we recommend also taking out the fuse and visually checking it.

Sometimes the fuse casing or metal strip may be physically damaged, or the fuse might have a loose contact with the fuse panel.

You won’t be able to see this with the tester or multimeter.

The damaged fuse may cause an occasional loss of contact, meaning that sometimes the appliance works, and sometimes it doesn’t. A very tricky problem and one that can cause lots of unnecessary repairs.

Have this in mind when testing a car fuse, just in case.