4 Symptoms of Bad Alternator System in a Truck

In this guide, we will look at how to know when you have a bad alternator in your truck. The electrical system is an integral part of your truck, which is the source of entertainment, gives you vision at night, and enables you to signal other road users. The electric system will allow your wipers to work effectively in heavy rain. There must be a power source for all these electric parts to function effectively. The alternator is the primary power producer of any truck. As the name suggests, it changes the energy from the engine to that which can be utilized by the electrical parts of your truck.

The alternator plays the role of charging the battery of your truck, and it is connected to the battery, so the battery does not run out of power. The work the alternator does stresses it, and at some point, it breaks down. This guide will focus on some symptoms that will let you know if your alternator is faulty.

4 Symptoms of a Bad Alternator

The battery warning check light on the dashboard is the most common symptom of a bad alternator, sometimes your headlight will not be stable when put on. You may also hear a funny noise from the engine. Now you know the most common signs, having an in-depth look at them will cause you no harm.

Battery Warning Light

The appearance of a battery warning light on your dashboard clearly indicates that your alternator is faulty. How will the appearance of the battery check tell you that your alternator is defective? When your ignition is on, your battery’s voltage is over 13 volts. A healthy truck battery has 12 volts, which will shoot to 14.2 when the alternator charges it. When the voltage drops to 13 volts and the ignition is on, the battery check light will appear on your dashboard.

Dim Headlight

The headlights consume a lot of power, and thus they need a lot of electricity. When they receive adequate power, they will be very bright. As your truck runs, the headlights will consume the light on the alternator. A faulty alternator will not supply adequate power to the headlights, making them not light bright.

Battery Starts to Drain Faster

You will be charging your battery regularly, but it keeps draining even if it is still healthy. When you note this, the alternator could be faulty. A faulty alternator will supply the battery with inadequate power, and other electric parts of the truck will depend on the power from the storm, which will drain it very fast.

Funny Noise from the Engine

The alternator has bearings and spinning components that are metallic. If it experiences any physical damage, your truck will produce a loud squealing or banging nose. Faulty bearings mainly cause noise in the generator. You can easily spot your truck’s alternator from the engine bay, so you can easily open it and check the cause of the noise. This is one way of knowing whether you have a bad alternator.


The above four are some common symptoms of a bad alternator, knowing them quickly lets you know the right area to check if you experience any of these signs. This is something that most people do not keep in mind when doing regular truck maintenance.

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