How to Test Car Fuses Using a Test Light

Hi. I'm Mike from 1A Auto. We've been selling auto parts for over 30 years.

If you have something in your vehicle that's not working, like a light or a radio, one of the possibilities is it could be a blown fuse. Over here, we have an under-hood fuse box. Generally there'll be a cover over it, so we'll take the cover off this one. Generally, on the back side of the cover there is a key that shows you which fuse is which.

One of the ways you can check it is to find what's not working, like the interior lights, and you could pull that individual fuse and try to look and see if it's damaged.

As you can see, we have the blown fuse here. The blown part is right here. This is another blown fuse, and it's very hard to see the broken U shape in there. I'm going to show you another way to test if you have a blown fuse.

One way to check your fuses is with a test light. I'm going to show you how to do that. We actually sell this test light at 1AAuto.com. The first thing you're going to do is test the test light and make sure.

We're going to crimp this to the negative battery terminal, and then we're going to test it at the positive and make sure the light actually works. That way you know that you have a good connection on the negative.

Now, one way to test these fuses, on the back of a fuse, there's a little pin, and you can actually, with the test light, you can go in each pin. If the light lights up on both sides, then you know the fuse is good. Just like that.

So you can check each fuse, and then if you go to a fuse and one side lights up and but the other side doesn't, that fuse is bad. Like this one, this fuse is blown. But if we check other ones, the other ones light up.

Once in a while, you'll come to an instance where the light won't light up at all. That just means there's no power going to the fuse. So that item isn't on, whether it needs the key to be on or accessory, that's why that would not have power. That does not indicate a blown fuse. But power on one side, no power on the other, that is a blown fuse.

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