These Are the Most Common Symptoms of a Failing Alternator

Found in all modern vehicles, the alternator is a type of electric generator that converts mechanical energy into alternating current. It charges the battery and helps power the headlights, wipers, electric windows, and other accessories.

Like all other components, it’s susceptible to wear and tear, and its internals will eventually fail, but not without some warnings.

Dashboard warning light

The most common way your car will let you know that something is wrong is through a dreaded warning light. In this case, the battery-shaped symbol will light up, or, on some cars, an ‘ALT’ or ‘GEN’ icon will pop up.

If the alternator’s voltage output drops below a pre-set limit, the dash light will come on. However, if this happens when your car is stopped and disappears when you drive, it means the output returns to normal. This is the first sign that your alternator isn’t working properly, and you should not ignore it.

Dimming or flickering headlights

If only one of the headlights is acting up, then the problem might be a bulb, but if both dim or flicker, it means that they are not receiving enough power.

Sometimes, this happens at low RPMs, but they return to normal brightness and steady light when driving at higher RPMs. If this happens, the alternator is the main suspect.

Most modern cars are electronically programmed to prioritize the electrical power and send it to the components that need it the most, so this symptom may not occur on all vehicles.

Dead battery

There’s no worse feeling than turning the key in the ignition or pressing the engine start button and noticing the car doesn’t start. In most cases, this occurs when the battery dies.

Batteries have a limited lifespan, too, but if your car is not that old or you changed the battery relatively recently, this means that the alternator has ceased to function and cannot recharge it.

A quick way of diagnosing which component is causing this problem is to jump-start the car but quickly remove the cables. If the battery is the problem, the car will continue to run; if it suddenly stops, then it’s the alternator.

Electronics are malfunctioning

If the alternator struggles to produce enough electrical energy, some of your electric components will start to act up. Some people have noticed that the windows drop down and go back up more slowly than before, others have noticed that the seats take longer to heat or that this feature does not work at all.

The best way to make sure that the alternator is the culprit is to try and use two of them at the same time. For example, turn on the radio/audio system and drop down one window. If one or both components are malfunctioning, then you need to get the alternator checked immediately.

Clicking or rattling sounds

These unusual sounds could also be a sign of a failing alternator, especially when they are accompanied by one or more of the symptoms listed above.

If you lift the hood and notice these sounds coming from the area where the alternator is fitted, it means that its internals are worn out, and it’s struggling to function correctly.

None of these symptoms should be ignored, and we recommend you take the car to a specialist immediately and get your alternator checked.

It can either be repaired or replaced, with the first option being by far the cheapest. However, don’t expect a refurbished alternator to last as much as a new one because many of the aftermarket repair kits are of inferior quality compared to the components used by the manufacturer.