Blown Alternator Fuse Symptoms: Location, How to Fix it

Blown Alternator Fuse Symptoms

An alternator fuse is a crucial component in a car’s electrical system. Its main function is to protect the alternator from electrical damage caused by a surge in voltage. In this article, we will discuss the importance of the alternator fuse, how it works, blown alternator fuse symptoms, and what to do if it blows.

What is Alternator Fuse?

The primary alternator fuse acts as a circuit protection device. When there’s excessive current flow, the fuse blows to prevent a circuit overload that could lead to melted wires, damaged components—and a potential fire.

An alternator fuse is a type of fuse that is used to protect the alternator in a vehicle’s electrical system from overloading or short-circuiting. It is typically located near the alternator and is designed to blow if the alternator begins to fail or if there is an electrical problem in the system.

The alternator fuse is an important component in the vehicle’s electrical system, as it helps to prevent damage to the alternator and other components, and can help prevent costly repairs. In addition, a damaged alternator can lead to a dead battery, leaving you stranded on the side of the road.

How does an Alternator Fuse Work?

An alternator fuse breaks the electrical circuit if the current flowing through it exceeds a certain level. The fuse is made up of a metal wire or filament that is encased in a heat-sensitive material.

When the current flowing through the fuse exceeds the rated level, the heat generated causes the heat-sensitive material to melt or vaporize, breaking the circuit and preventing further current flow.

In the case of an alternator, the alternator fuse is designed to protect the alternator from damage caused by a short circuit or overloading. If a short circuit or overloading occurs, the large amount of current flowing through the alternator will cause the alternator fuse to blow, breaking the circuit and preventing further damage to the alternator.

Where Is the Alternator Fuse Located?

The location of the alternator fuse and fusible links can vary greatly depending on the make and model of a vehicle. In some vehicles, the alternator fuse may be located in the main fuse box under the hood, while in others it may be located in a separate fuse box or electrical panel.

There are four fuses in total. Two are in the fuse box at the left side of the dash, those are fuses 8 and 27. Both 10 amp. Then there are two more under the hood in the battery junction box on the driver’s side. Those are fuses 11 (15 amp) and FB (120 amp).

To determine the location of the alternator fuse on your specific car, it is best to consult the owner’s manual for your vehicle.

The manual will typically include a diagram of the vehicle’s electrical system, including the location of all fuses and fusible links. Additionally, the manual will often include instructions on how to access and replace the alternator fuse, if necessary.

Blown Alternator Fuse Symptoms

Blown Alternator Fuse Symptoms

It is important to note that alternator fuses do not blow for no reason. If an alternator fuse is blown, it means a problem in the electrical system must be addressed.

The only exception is if the vehicle has been worked on or jump-started recently and mistakes were made, such as jump-starting the battery with the cables reversed or grounding the alternator’s battery terminal with a wrench, which can cause the fuse to blow.

When the alternator fuse is blown, it can cause a variety of problems that mimic a bad alternator.

Common symptoms associated with a blown alternator fuse include:

1. Dead Battery

A blown alternator fuse can cause the battery to lose charge, resulting in a dead battery. The alternator is responsible for recharging the battery while the car is running.

If the alternator fuse is blown, the alternator will not be able to function and charge the battery, causing it to lose power and eventually die.

This can lead to difficulty starting the car, or even the car not starting at all. If the battery is dead, it’s important to check the alternator fuse and have it replaced if it is found to be blown.

2. Lighting Issues

A bad alternator fuse can cause the headlights and other electrical systems to dim or flicker. This is because the electrical current is not flowing properly through the system, causing a loss of power to the lights.

The alternator is responsible for providing power to the electrical systems in the car, and if the alternator fuse is blown, the alternator will not be able to function properly, leading to a lack of power to the lights.

This can also lead to other electrical problems such as the radio, power windows, or other accessories not working properly.

3. Warning Lights

If the alternator fuse is blown, the battery or charging system warning light on the dashboard may come on, indicating a problem with the electrical system. This is because the fuse is not able to properly protect the alternator, and the vehicle’s computer detects a problem.

When the warning light comes on, it is important to have the alternator fuse checked and replaced if necessary.

4. Other Electrical Oddities

A blown alternator fuse can cause other electrical problems such as strange noises, lack of power, or the engine to stall. This is because the fuse is not able to protect the alternator, and other electrical components may be affected by the loss of power.

For example, you might hear whining or buzzing sounds coming from the alternator or other electrical components. This can also cause the engine to stall or have a lack of power, making it difficult to drive.

Additionally, if you experience intermittent power loss or electrical problems, it’s best to have the alternator fuse checked as it may be the cause.

How to Replace a Blown Alternator Fuse?

Replacing a blown alternator fuse is a relatively simple process that can be done with a few basic tools. Here’s a step-by-step guide:

  • Locate the alternator fuse. The alternator fuse is usually located near the alternator and is typically marked with a label or diagram in the vehicle’s owner’s manual.
  • Disconnect the battery. Before working on the electrical system, always disconnect the battery to prevent electrical shock or damage to the vehicle’s electronics.
  • Remove the fuse. Use the fuse puller tool or a pair of needle-nose pliers to gently remove the blown fuse from its socket.
  • Inspect the fuse. Check the fuse for any visible damage, such as melted plastic or a broken filament. If the fuse is damaged, it will need to be replaced.
  • Replace the fuse. Insert a new fuse of the same amperage rating into the socket. Make sure the fuse is securely seated and the plastic is not cracked or melted.
  • Reconnect the battery. Reconnect the battery and test the electrical system to ensure that the alternator is working properly.
  • Check the cause. Check the cause of the blown fuse, and fix it if necessary, or consult with a mechanic if you are unsure.

It is always a good idea to consult the vehicle owner’s manual or take the vehicle to a professional mechanic if you are unsure about anything.


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