What Fuse Controls the Alternator? Causes and Fixing of Blown

The alternator is essential to a car’s electrical system, providing power to the various circuits. This component is controlled by a fuse, which helps to prevent system overloading, protecting it from harm and ensuring it keeps running smoothly.

The alternator fuse is responsible for regulating how much power flows through the system and will break the circuit if it is overloaded.

In this article, we will look at what fuse controls the alternator, where it is located, symptoms of a blown alternator fuse, how to prevent the fuse from blowing, and how to replace a blown alternator fuse.

blown alternator fuse

What Fuse Controls the Alternator?

A car’s alternator is controlled by a high-amperage fuse or fusible link between the battery and the alternator. The primary assignment of the fuse is to stop excessive current from flowing through it and damaging delicate electrical systems in the car.

When there’s a sudden flow of excessive current, the alternator fuse blows instead of allowing a circuit overload that is capable of melting wires, damaging vital electrical systems, and ultimately resulting in a fire outbreak.

A blown alternator fuse will make it impossible for your alternator to charge your car’s battery. It will also hinder the supply of power to various electrical systems. Typically, the alternator fuse function is generally for safety purposes.

Where is Alternator Fuse Located?

A standard alternator fuse is typically located in the fuse box within the engine compartment. Usually, the fuse is larger than the regular blade fuses used for smaller electrical components like tail lights because an alternator requires a high amp fuse.

In some cases, the inline alternator fuse or fusible link for a vehicle can be situated between the positive lug of the car’s battery and the positive alternator cable.

Alternatively, in some vehicles, this fusible link may be found running between the positive leads of the car’s battery and the primary positive connection on the fuse/junction box.

Symptoms of Blown Alternator Fuse

Battery warning light, dead battery, dimming lights, difficulty in starting engine, and other electrical malfunctions, are common symptoms of a blown alternator fuse.

Here’s an insight about the blown alternator fuse symptoms listed above.

Warning light illumination

Virtually all operations in your car can be monitored through the dashboard warning lights. The alternator’s operation is not an exception. Therefore, if your alternator’s fuse blows, it will trigger the illumination of the battery warning light.

The occurrence can also trigger the check engine light and other related warning signals because of their close alignment in operation.

Dead battery

A blown fuse will make it impossible for your car’s alternator to charge the battery and supply the required power to the various electrical components in the vehicle.

When this happens, the battery power will gradually deplete until it dies since the alternator is no longer charging it. A dead battery will further lead to many other malfunctions.

Dimming lights

The headlights, taillights, and other lighting systems depend on the alternator for power supply. Therefore, if the fuse suddenly blows, you will start experiencing inconsistency with the brightness of the lights.

Difficulty in starting engine

This is more like a secondary symptom emanating from a dead battery. Since your car depends on the battery and other mechanical and electrical systems to turn on the engine, starting the vehicle with a blown alternator fuse will be difficult.

Other electrical malfunctions

Modern vehicles with several related computer systems depend on the charging system to power their full operations. Hence, a blown fuse will eventually alter the operations of various electrical systems and lead to unexpected multifaceted malfunctions.

What are the Causes of a Blown Fuse?

An alternator fuse doesn’t just blow for no reason. If you discovered a blown alternator fuse in your car, one or more of these factors may be responsible.


Running too many electrical systems simultaneously in your car can overload the alternator, thereby affecting the fuse. Overloading an alternator can cause it to draw too much current, which can eventually blow the alternator fuse. 

Inappropriate alternator fuse 

Using an undersized fuse can also be a cause of blown alternator fuse. Replacing a larger fuse with a smaller alternator fuse size can affect the alternator’s efficiency, thereby blowing the fuse.


Corroded connections due to oil leaking or other reasons can cause a high resistance and current overload in the alternator’s circuit. When this happens, a blown fuse is certainly imminent when you least expect.

Excessive current

Excessive current flow is one of the major reasons why alternator fuses blow. There’s a maximum expected voltage that the fuse is designed to handle. If too much current flows through the component, you will most likely have a blown fuse.

How to Prevent Alternator Fuses from Blowing

Like the famous maxim – “Prevention is better than cure,” so it is for every car part. It is better and cheaper to prevent them from being damaged than trying to fix them when they’re defective. The following are ways to prevent alternator fuses from blowing.

Check wiring connections regularly

Always check and clean your alternator as well as battery wiring regularly to ensure that all the connections are in good condition.

Loose or corroded connections may be drawing too much current and can easily blow the alternator fuse.

Replace loose or damaged wires

Next, ensure to replace any loose, damaged/pinched wires or frayed insulation. The cost of fixing these wires cannot be compared to repairing a defective vehicle alternator. So, ensure to respond to challenges in their infancy.

Maintain optimal amperage and voltage

Remember that the excessive flow of current is one of the leading causes of a blown alternator fuse. Therefore, it is vital to ensure your car’s alternator is operating within its rated amperage and voltage.

Replace worn bearings

Lastly, it is crucial to monitor the condition of the alternator’s bearings constantly. If the components begin to manifest signs of wear and tear, kindly replace them as soon as possible to avoid any further damage, such as blowing up the fuse.

How to Replace Alternator Fuse

Replacing your vehicle’s blown alternator fuse is pretty simple. However, identifying the exact fuse among the numerous fuses in the box can be a little bit challenging. However, you can follow the procedure below to replace your car’s alternator fuse.

Step 1: Identify the location in your owner’s manual

Check your car manual and find out where the fuse is located. It is mainly located on the fuse box in the engine bay.

Step 2: Open your car’s hood and the fuse box

Once you know the alternator fuse location from the manual, go ahead and open your car’s hood and open the fuse box.

Step 3: Identify and remove the alternator fuse

Use the fuse box diagram to locate the alternator fuse. Then, carefully pry out the fuse a plier.

Step 4: Replace the alternator fuse

Finally, ensure to get the recommended alternator fuse and replace it carefully by pushing it into place. You can easily push it in with your fingers. Then, place back the cover of the fuse box and close the hood.


Undoubtedly, owning a car comes with a couple of responsibilities. One of such is the ability to replace a blown alternator fuse. This is a pretty simple DIY operation. However, you must know what fuse controls the alternator.

Every single detail you need to know about the alternator fuse has been provided above in this article.

Ensure to follow the recommendations above to prevent your alternator fuse from blowing. However, if it’s already blown, kindly follow the alternator fuse replacement procedure to fix the issue.


Mr. Shafiqule Islam is a graduated Mechanical Engineer and has more than 15 years experience of repairing and maintenance of different brand vehicles like Toyota, Mitsubishi, Ford, Mercedes, BMW etc. He is also giving training to Mechanics. He has started writing to share his practical knowledge to Vehicle Owners, Drivers and Mechanics to keep their cars at best fit.

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