How do you know if car fuses are bad?

If a component or an accessory such as the radio, or lights doesn't work, than that is a good sign a fuse is blown. When you suspect that a fuse is bad, find out where it is in your owners manual. Most cars have 2 fuse boxes. One should be somewhere under the hood. The other should be located behind a panel under the dashboard on either the drivers, or passenger side of the car. When you find the right fuse box, look at the diagram on the lid of the fuse box, study it carefully, and determine which fuse is the one that you are looking for, such as; fuel pump, or headlamps. If there isn't a diagram, check the owners manual, it should have a list numbering them. When you find the fuse, gently pull it out of its place, and inspect it. You will see a bridge going from one side of the fuse to the other. If the bridge is connected, that the fuse is fine. If there is a gap in the bridge, than that means the fuse is bad. If you are unsure, pull out another fuse from a part that you know works; and compare them. Be sure to replace a fuse of the same amperage (the number on the top of the fuse) if you replace it your self.