How to check your car’s fuses
Thursday 13th July 2023
What is a car fuse?
A fuse is typically a metal wire strip that burns or melts when a current that is too strong passes through it, interrupting the flow of electricity and breaking or blowing the circuit to a device. A car fuse, most commonly a blade-type fuse, is a coloured shell of plastic with two metal prongs that can stick into a socket. These fuses can be mounted into fuse clips, holders or blocks depending on the application. A car will have many fuses to protect various electrical components from high-voltage occurrences.
What can cause a car fuse to blow?
A blown fuse can cause a minimal electrical problem such as indicator, radio or interior lights failure, or it can affect internal factors such as climate control with heating and cooling systems. In some cases, a blown fuse can become a more serious issue and can prevent your vehicle from starting altogether. Usually, a fuse can blow due to a device malfunctioning. Reasons for an automotive fuse to blow include:
- Faulty wires
- Mechanical motor issues
- Defective switches
How to check your cars fuses
If you suspect a fuse has blown in your car, we recommend reaching out to professionals to err on the side of caution. If you are looking to check a fuse yourself, follow these steps.
Step One
There are many locations a fuse box can be located, depending on the make and model of your vehicle. If you are unsure where to look, consult your user manual to determine which fuse box controls which circuit. Fuse boxes may be commonly located in the following:
- The boot
- Under the bonnet
- Underneath the back seats
- Beneath the dashboard
Step Two
Once the fuse box has been located, look for a diagram that explains the function and location of each fuse. If you are unable to spot this diagram, you will have to use a test light. We recommend using an LED computer-safe light.
The ignition should be on, but the engine should be off. This method is known as ‘second key’ or ‘key on engine off’ (KOEO). Once the ignition is on, attach the clip for the test light to any metal that is exposed. Use the probe to touch the end of each fuse.
If the test light illuminates on both sides, the fuse is working properly. If the test light is only illuminating on one side, the fuse has blown.
Step Three
Turn the car off completely and locate the fuse to remove it using a fuse puller. Fuse pullers are typically located inside the fuse box, however if you can’t find these, a pair of needle-nose pliers will be sufficient.
At this point, you can begin inspecting the fuse. Whilst gripping the fuse with the puller, hold the fuse up to the light and take a look through the translucent bodywork. Here you should see a thin metal wire.
If the wire appears broken, no longer holds a continuous thread or is in two pieces – the fuse has blown. If this appears to be the case, the fuse will need to be replaced.
The best way to locate any damages to your fuse box is to book in for a regular car service. Find out more about what’s included in a car service or locate your nearest Formula One Autocentre. Alternatively, contact our helpful team to find out more.
