10 Symptoms of a Failing Alternator

Alternators are crucial when it comes to the overall functionality of a car. In fact, without an alternator, you wouldn’t be able to start a car. Like other components of your car, it is susceptible to damage after long use or in case of accidents.

In this article, we share the causes of a faulty alternator and 10 symptoms that you need to look out for. For these and more, let’s dive in!

What is an alternator?

This is an electric generator that supplies the vehicle with electricity by converting DC into AC. When a vehicle is running, a lot of components consume energy which can easily drain the battery in an eyelash.

This is where the alternator comes into play. It enables the conversion of mechanical energy into electricity that in turn charges the battery. Without an effective alternator, your car is as good as dead. So, what causes alternators to go bad? Let’s have a look!

Causes of a bad alternator

1. Broken computer

Modern cars come with in-built computers that automatically diagnose your car to identify any faulty component, and the alternator is one of them. They also ensure that each part of your car receives the needed electric power. In the event of a faulty computer, it can prevent the alternator from charging the battery.

2. Wiring problems

The alternator is supplied with power through numerous cables. If any of these cables are loose or worn out, it can cause the alternator to stop working effectively. Ensure that the wires are precisely plugged into the alternator.

3. Faulty fuse

Like most electric components, the alternator relies on the fuse to keep it functioning. Unfortunately, a fuse can blow out in case of a power surge making the alternator to stop charging the battery. To identify the fuse, you can refer to the car owner’s manual.

4. Broken belt

The belt and pulley are what supply the alternator with mechanical energy. And since they are not sturdy, they are susceptible to breaking down. When they do, they cease to supply the energy and eventually the battery runs low causing the car to stop while driving.


Now, let’s look at the signs of a failing alternator.

What are the symptoms of a failing alternator?

1. The indicator light comes on

Fortunately, there is an indicator light on the dashboard that alerts you in case the alternator is malfunctioning. It either comes in a battery icon or abbreviations “GEN” or “ALT”. Whichever the case, it will come on once the computer system detects damage to the alternator.

In the early stages of a dying alternator, the indicator may flicker since the voltage to the alternator changes rapidly. Also, you can witness this when you use more power while driving. This is the perfect time to have it checked instead of waiting until it fails completely.

2. Dim headlights

Dim headlights are another indicator of a failing alternator. Typically, when the RPM increases, the headlights grow brighter, but when it reduces, they become dim. This indicates that the alternator is not supplying sufficient energy to power the car.

Besides, most modern cars come with a safety measure that cuts power to components such as radio before doing so to the headlights. If you witness this pattern, it is time you replaced your alternator.

3. Flickering lights

Another common symptom of a failing alternator is flickering lights. That is, they randomly become bright, then dim. This indicates that there is not sufficient energy to keep the components running. And the number culprit is a dead alternator.

To ascertain that it is the alternator with the problem, you can try to heat your seats or turn on the radio. If the flickering persists, then you have a failing alternator.

4. Dead battery

While a battery might die due to other reasons, a faulty alternator can also cause it to die. This is because it is not charging the battery accordingly. That said, car batteries are not built to last rather they serve you for a few years and suffer a gradual death.

So how can you tell that it’s the alternator with the problem? Simple! Just jump-start the battery and remove the wires immediately. If the car does not switch off, the problem is not the alternator. But should it switch off after a few minutes, then you have a faulty alternator that needs replacement.

5. odd noises

A rattle sounds in your car can be due to a wide array of problems. However, a failing alternator can also cause such noises, especially in the engine. This is because of failing engine bearings. Fortunately, it’s not common for cars to reach this stage since other indicators will have warned you. This is why it is important to pay attention to the above symptoms since repairing a broken engine is expensive.

6. Strange and nauseous smells

Ever been close to burning rubber or plastic? That’s the smell you need to look out for. It comes from under the bonnet. This indicates that the alternator is overworking hence causing the generation of heat that burns the cables and wires.

The smell of burning rubber is due to the alternator belt not seating properly hence enormous friction. The wires could be burning since electricity is not flowing sufficiently. You should have the wires checked to avoid further damage.

7. Car stalls

Another common indicator of a failing alternator is the car failing to start. This is because it is not supplying the spark plugs in the ignition system with enough electricity. Other times, the car may start and stall as you drive. This shows that the alternator is not charging the battery hence the spark plugs fail.

8. Failing accessories

This could be the radio not turning on, seats not heating, or windows failing to lower. When the alternator fails, the computer system of your car might act erratically affecting digital communication causing most accessories to stall. To avoid further complications, you should avoid using the accessories until you visit a garage for assessment.

9. Loose connections

If the battery icon does not go on but the battery fails to charge, it could be due to faulty wires that supply the battery with electricity. When this happens, the alternator produces enormous energy to overcome resistance from the wires. This resistance causes heat buildup which causes the wires to burn.

10. Loose belt

Although not common, loose alternator belts can hamper the performance of the alternator. Make sure that the belt has ample tension to keep it tightly secured to provide the alternator with ample mechanical energy.

Wrap up!

You should never ignore any of the above symptoms since doing so might cause damage to the engine. Always look out for the indicator light as this is the first sign of a failing alternator.