In electrical systems, fuses serve as safety mechanisms as they help prevent current overflow which can damage sensitive components and circuits. Passenger vehicles have more than 12 fuses to protect the various electrical components from high voltage. Most of these fuses are usually rated at 32 volts and can be found in one of two fuse boxes located in your car.

So, how do you tell if a fuse is blown? Want to know the actions that cause a car’s fuse to blow out?

Read on.

What Actions Can Cause a Car’s Fuse to Blow Out?

There are several reasons that the fuses in your car keep blowing out. The first reason is a short circuit. In passenger vehicles, fuses protect the wiring system and electrical components.

When a short occurs in the electrical system, it will cause the fuse to blow instead of the wiring system melting or overheating. In electrical terms, a short is a poor connection between two ends. When it happens, an electrical overload occurs in the circuit.

Besides a loose connection, a short circuit may occur as a result of frayed wires. If one of the wires is frayed and exposed, it can touch the ground or metal frame causing a short in the circuit. This is because the wire will move around and come into contact with a metal surface causing intermittent shorts.

A malfunctioning electrical device can also cause the fuse to blow. For example, damage to the power locking system or windshield motor may cause the fuse to blow out. This is because the malfunctioning component will cause a higher amount of current to flow and overload the system. This action will short the circuit.

If a leak is present in your vehicle and a conductor is exposed, the fluid could wet the wiring and connection points. If this happens, the conductor may cause the electrical components to short. Lastly, you may replace a bad fuse with an improper one.

Fuses can continue blowing out if you replace a bad fuse with an improper one, especially a fuse with an incorrect current rating. To avoid this, always check the vehicle’s manual. It should contain details showing the correct amperage rating for every fuse in your vehicle. If unsure what fuse to use, consult a professional.

How Long Does It Take a Fuse to Blow?

The speed at which a fuse blows usually depends on the type of current used to manufacture the fuse and the amount of current flowing through it. The operating time of a fuse is not a fixed interval. However, it does decrease as the current increases.

Fuses have different operating times compared to current. For a standard fuse to blow out, it may require twice its current rating while a fast blow fuse may blow in 0.1 seconds as it will require twice its current rating.

When it comes to a slow blow fuse, it may take tens of seconds to blow. To do so, the fuse will require twice its current rating. When selecting fuses, it all depends on the load characteristics.

Some devices may use an ultrafast or fast fuse as the device heats rapidly when excess current flows. Fast-blowing fuses are usually designed for sensitive electrical equipment where even a short exposure could be very damaging.

We also have the time delay fuse or slow blow fuse that allows current above the rated value of the fuse to flow over a short period without the fuse blowing. Such fuses are commonly used in motors as they can draw larger than normal current levels for several seconds.

Can You Drive a Car With a Blown Fuse?

Driving your car with a blown fuse can cause different problems. This usually depends on the type of fuse blown and the equipment it controls. For example, if the fuse for your headlights blows, then your headlights will not work.

Another example is where the fuse for your electrics blows out. If this happens, your car may fail to start or stall. If a fuse blows and your car runs, one or more functions will be severed until you physically locate and replace the blown fuse.

So, can you still drive your car with a blown fuse? 

Passenger vehicles have more than 12 fuses. Some of these fuses usually serve power to more than one piece of electrical equipment. A car can run with a blown fuse but because that particular item will not be working such as headlights or taillights,  you will put other road users at risk especially when driving at night. So, if a fuse blows, replace it with an equivalent one.

Remember, using a fuse with a higher current rating could fry the electrical components and wiring system or even start a fire.

How Do You Tell if You Blew a Fuse in Your Car?

One way to tell if a fuse blew out in your car is when one of the components stops working. For example, if your headlight fuse is blown, then the headlights will not work. This is the same for other items in your car such as the radio, taillights, indicators, interior lighting, and others.

This can also extend to sophisticated systems in your car such as chassis electronics, powertrain electronics, driver assistance technologies, and others. When a fuse blows, you need to locate the bad fuse and replace it.

The most accurate way to test if a fuse is bad is with a multimeter. The multimeter allows you to test for continuity between its two ends. If the fuse is blown, there will be no continuity between its two ends.

Final Thoughts

When a fuse blows, the electrical system or component it’s connected to will stop working. This is because the fuse interrupts the flow of current to the device. Basically, the circuit is broken. If you notice an item in your car is not working, the cause could be a blown fuse. We recommend that you have the blow fuse replaced with an equivalent one.

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