How to check car fuses

A fuse is a low resistance device that protects a circuit from overload. It is a short piece of wire that melts and breaks apart when subjected to excess electrical current. The fuse is...

A fuse is a low resistance device that protects a circuit from overload. It is a short piece of wire that melts and breaks apart when subjected to excess electrical current. A fuse is connected in series with the circuit it protects.

A blown fuse usually causes a short or overload in the circuit. The most common blown fuse in a car is the 12V fuse, also known as the cigarette lighter. This often happens when a cell phone charger is left in it for a long time, or when a random coin is dropped into an unprotected outlet.

The fuse box is located in the vehicle and contains the fuses. Some cars have multiple fuse boxes with many different fuses. If something electrical in your car has suddenly stopped working, start by checking the fuse box and have a certified mechanic look at and diagnose any electrical problems.

Part 1 of 4: Locate the fuse box

Necessary materials

• flashlight
• Needle nose pliers or fuse puller
• test light

Most cars have more than one fuse box - some cars may even have three or four. Car manufacturers tend to install fuse boxes in different locations depending on the brand of car. Your best bet is to refer to your owner's manual to find the right fuse box and also to determine which fuse controls each circuit.

Part 2 of 4. Visual inspection of fuses

Most fuse boxes have a diagram showing the name and location of each fuse.

Step 1: Remove the fuse. With the vehicle completely shut off, locate the appropriate fuse and remove it by firmly grasping it with the fuse puller stored in the fuse box or with a pair of pointed pliers.

Step 2: Inspect the fuse. Hold the fuse up to a light and check the metal wire for signs of damage or breakage. If you see any of this, you will need to replace the fuse.

Part 3 of 4: Use Test Light

If you don't have a fuse diagram to identify a specific fuse, you can test each fuse individually with a test light.

Step 1: turn on the ignition: Turn the key to position two in the ignition switch, also known as key on, engine off (KOEO).

Step 2: Check the fuse with a test light.. Attach a test light clip to any bare metal and use a test light probe to touch each end of the fuse. If the fuse is good, the control lamp will light up on both sides of the fuse. If the fuse is defective, the control lamp will light up on one side only.

• Functions: Use a computer-safe test light, preferably with an LED light, as testing unknown fuses with an older test light may result in excessive current. If you check the airbag fuse, it may blow - be careful!

Part 4 of 4: Replacing the fuse

If a damaged fuse is found, be sure to replace it with a fuse of the same type and rating.

• FunctionsA: Fuses are available at any auto parts store, hardware store, or dealer.

Identifying and replacing a damaged fuse on your own can save you time and money. However, if the same fuse is blowing repeatedly or if certain electrical components are not working, it is advisable to enlist a certified mechanic to inspect the electrical system to identify the reason the fuse keeps blowing and replace the fuse box or fuse for you.