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How To Tell If Fuse Is Blown In Your Car: Types + Causes

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A blown fuse can lead to damaged systems, loss of performance, and costly repairs. Here's how to tell if fuse is blown in your car, and what you can do.

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  • How To Tell If Fuse Is Blown In Your Car: Types + Causes

Car fuses – also known as "automotive fuses" – are vital components that, like regular fuses in your home, are specifically designed to protect the electrical wiring of a car. Their primary function is to offer protection against overcurrents and short-circuiting. In the event of potentially dangerous levels of current threatening to pass through, a car fuse simply disconnects the relevant circuit.

But what happens when one of these fuses blows? Here's how to tell if fuse is blown in your car, and what you can do about it:

How Do Automotive Fuses Work?

Car fuses come in all shapes and sizes. Each variation is best suited to a specific application or electrical part in the car. The most common type is the blade fuse. These have a coloured body made of plastic, with two metal prongs that stick into a socket. Depending on the application, these fuses can be mounted into:

  • Fuse holders
  • Clips
  • Blocks

What Does A Blown Fuse Look Like In A Car?

In a car, a blown fuse will manifest itself as a minor electrical problem, such as the failure of:

  • Interior lights
  • Radio
  • Turn signal indicators
  • Internal features, such as climate control

Sometimes, though, it can be as serious as preventing the car from starting altogether. That makes it important to know why a fuse might blow, so you can stop it from reaching this point.

Why Do Car Fuses Blow?

When fuses "blow," it's because the ribbon that allows the current to pass through the fuse melts. If the current were allowed to continue, it would also damage the circuit, especially with notably strong currents. Instead, the fuse shuts down the pathway and stops the current from traveling to harm the circuit.

Excessive current comes from an electrical component drawing more than it can handle. This is usually due to a device malfunctioning. Common reasons for a blown automotive fuse include:

  • Defective switches
  • Faulty wires
  • Mechanical issues with the motor
  • Rogue faults with electrically-motivated parts

How To Check A Blown Car Fuse

If one of your interior lights is no longer working, or your indicator appears to be broken, chances are that a fuse has blown. Your first response should be to call a local garage, such as Autofusion, for an evaluation and repair package. Dealing with the electronics in a vehicle requires not only a steady hand, but also expert knowledge.

If you want to confirm that a fuse is indeed blown, however, you can follow these steps:

1. Locate The Fuse Box

Depending on the vehicle, there could be as many as four fuse boxes located in various parts of the car. It's important to find the one with the blown fuse.

For help, check your owner's manual to determine which fuse box controls which circuit, and then go from there. In general, fuse boxes are commonly placed:

  • Under the bonnet
  • Beneath the dashboard
  • Underneath the back seats
  • In the boot

2. Locate The Individual The Fuse

When you have located the right fuse box, it's time to identify the suspected fuse. Most fuse boxes have an intricate diagram explaining the function and location of each fuse.

If your fuse box does not come with this, use a test light. Be sure to pick a computer-safe one with an LED light. To conduct the test, switch the ignition on, but keep the engine off. This is known as the "KOEO" or "second key" position.

Once the ignition is on, attach the clip for the test light to any exposed metal. Then, use the probe to touch each end of the fuses.

  • If the fuse is working properly, the test light will illuminate on both sides.
  • If the fuse has blown, only one side of the test light will illuminate.

3. Remove And Inspect The Fuse

After switching the ignition back off completely, locate your fuse and remove it by grabbing it with a fuse puller. These are usually stored inside the fuse box. If there isn't one around, a trusty pair of needle-nose pliers will be sufficient.

Once removed, you can begin to inspect the fuse. Still gripping it with the puller, hold the fuse up to a light and examine it through the translucent bodywork. You should view a thin metal wire in there. If the wire is no longer a continuous thread and appears broken, the fuse has indeed blown. In this case, it must be replaced.

From here, it's highly recommended that you leave replacing the fuse to the professionals.

What To Do If Your Car Blows A Fuse

If your car has blown a fuse, call your local Autofusion centre. Dealing with electrical faults can be dangerous and risky. One false move and you may end up doing more harm than good to your vehicle's electrical system. Luckily, our experts are happy to undertake the job and get your car back into perfect working order.