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HomeTips & GuidesAutomotive Fuse Box Replacement – A Detailed Step-by-Step Guide

Automotive Fuse Box Replacement – A Detailed Step-by-Step Guide

About Automotive Fuse Box Replacement: Is your car experiencing electrical problems such as malfunctioning interior lights, radio issues, a dysfunctional dashboard, cameras, and the like? 

Even if you’re sure the battery and associated cables are perfect, these problems persist. 

While malfunctioning electrical systems have many causes, the fuse box is the main checkpoint before you call the mechanic. 

Today’s article discusses the automotive fuse box replacement, how you identify its issues, and how you wire it. 

What Is a Fuse Box?

Like the house, the car has many electronics, such as lights, radios, horns, and others, to function properly. 

While all these electrical systems draw power from the 12V battery, each has its voltage limit. 

Now, the voltage to a certain car electronic can sometimes surge which can blow the device.

 A fuse box comes into the car’s electrical systems to prevent this.

 Therefore, a fuse box controls the electrical current reaching a certain car gadget. 

It typically disconnects to prevent short-circuiting or overcurrent when the power is beyond the device limit.

How Do Fuse Boxes Work?

A fuse box gets current directly from the battery. Then, it features several cables that connect different circuits that require protection. 

For proper functioning, here are the main components of a fuse box and how they function:


A fuse is a small nonconductor gadget with two metallic (conductors) ends. Inside the small nonconductor is a conductor element that joins the two metallic ends.

 The device’s main function is to prevent the electrical wiring from passing excessive current. 

Each fuse comes inscribed with the number of amperes it can withstand depending on the thickness of the element inside. 

Now, if the amperage exceeds the fuse limit/rating, the element melts, thus disconnecting the circuit. 

When replacing the fuse, ensure you use the exact one with the same amperage and color codes to avoid issues.

 For example, a low amperage fuse blows faster, while a high one passes excess current that can blow your electronics.

Examples of car fuses

Examples of car fuses


Apart from the fuse, another component in the fuse box is a relay switch that uses electricity. 

The basic work of relays is to streamline the current while operating many electrical systems while preventing overloads. 

They mostly use electromagnetic coils, which are magnetized and demagnetized by electricity.


Diodes refer to inbuilt components in an electrical system, such as the relay, to prevent current backflow. 

Apart from letting current flow in only one direction in relay coils, diodes also prevent power spikes.

A photo of electronic diodes

A photo of electronic diodes

Car Fuse Types

While there are many types of fuses, blade fuses are the type that mostly feature in cars. They are in six different types and appear in varied amperage, designs, and sizes, as I list below:

  • Micro 2 (5A -30A)
  • Micro 3 (5A – 15A
  • Mini (2A – 30A)
  • Low mini (2A -30A)
  • Regular OTA/ATC (1A – 40A)
  • Max Heavy Duty (20A – 100A)

Where Is My Fuse Box?

While some modem vehicles have many fuse boxes, common ones have just two. You can find the one fuse under the hood near your car engine. 

This one protects the engine devices ege engine control unit, ABS motor, and cooling fan, among others. The second fuse box is under the hood near the steering wheel. 

This protects cabin devices such as power windows, radios, turn signals, and interior lights. 

Typically, this box comes with a cover that can pop easily using hands. 

Additionally, check your manufacturer fuse diagram box to help you identify your fuse location box depending on your issue.

How to Identify A Blown Fuse

As you may expect, some car components may cease working when the fuse blows.

 The next step is to use the fuse box diagram from your manufacturer to know the location of the fuse box. 

Then, identify the suspect fuse based on the diagram and the nonworking components. From there, remove the suspected fuse using tweezers or needle nose pliers. 

Then, inspect it physically for burns or melting of the inner element. 

Once you identify the blow fuse, replace it, but first, do a technical diagnosis to know why it blew.

While here in the fuse box, notice the empty fuse spaces and use them to store spare fuses. 

Holding a blown car fuse

Holding a blown car fuse

How Do You Wire A Fuse Box In Your Car?

Now that you know the location of fuse boxes, let’s see how you can wire a fuse box. 

Take precaution

Before you begin, switch off the battery and remove it if possible to avoid electrocution. Then, be aware of sharp edges that may injure you when working.

Start the process

To start the wiring task, you must use the fuse box diagram to know where the device is. 

Once you are there, clean the battery cable terminals at the fuse box end and then disconnect them. 

Remove the safe box by uncliping it and then depress the lock tab to remove it. Lastly, uncover the fuse box lid to reveal the fuses and relays.

Connect your Wire

Here, you will need the fuse diagram to reference the locations to connect the cables. Fortunately, it has color codes to help you locate and follow each wire for proper plugging.

Place all back

Once done, put the fuse box in its position, place the lid, and lock it like it was. Now, connect the battery cables and test your connection.

 Remember, if there is a blown fuse, you can replace it with another of the same amperage.

Wrap up

Now you know where your car fuse box is and how to check it when devices fail to work. Always check the fuse box first to avoid making unnecessary and expensive changes. 

Hi I am Christa, sales manager of Cloom.

I have extensive expertise and experience in wiring harnesses and I believe I can help you.

And we have a very professional technical team who can clearly understand the customer’s needs and give professional suggestions and solutions after receiving the drawings.

If you also have wiring harness needs, please send me the drawing so that we can give you our quote and start our business.

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