Bad Alternator Relay Symptoms (9 Things to Be Aware of)

If you’re an experienced driver, you’re likely to know if your alternator is causing car trouble.

However, there’s one component of the alternator called the relay that may be causing it to malfunction. Here’s what I found!

Bad Alternator Relay Symptoms

1. Warning Light On Dashboard

An alternator relay problem could manifest as a warning light on your dashboard.

Usually, when a problem with the alternator is detected by computer sensors, a dashboard warning light in the form of a car battery will illuminate.

However, on some car types, the warning light may appear as the words “GEN” or “ALT” to represent a problem with the vehicle’s primary power source: the alternator.

Therefore, these can indicate an issue with the alternator relay.

2. Alternator Is Malfunctioning

Aside from my point above, a malfunctioning or failing alternator may also be a sign of a bad alternator relay.

Generally, alternator relays isolate your charging system from the rest of your electrical system in case of shorts and other electrical issues.

As such, if the alternator relay is bad, this can cause the improper voltage to reach your car’s electronic control unit or ECU, resulting in severe damage to the computer and your car.

3. Damaged Relay Housing

Additionally, damage to the voltage regulator containing the alternator relay may be a symptom of a bad alternator relay.

Usually, the alternator relay controls the voltage by shutting off the current and preventing the battery from receiving too much charge from the alternator.

However, when the relay breaks, a power surge may flow through the relays, which can cause them to fail.

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In this case, the housing that contains the relay may become damaged, thus indicating that something’s wrong with the alternator relay.

4. Discharged Battery

In addition, a drained battery might also be a sign of faulty alternator bearings in addition to a broken alternator.

Typically, when the alternator malfunctions owing to bad bearings in this instance, the battery takes over as the car’s main power source.

As a result, this could result in the battery running out of juice, as batteries aren’t made to run your automobile for an extended period.

In other words, your car’s battery could die even if it wasn’t the original issue due to a damaged alternator relay.

5. Inconsistent External Light Brightness

Inconsistent External Light Brightness

Furthermore, a malfunctioning alternator relay may also be indicated by inconsistent headlight brightness.

Usually, the electricity needed for your car’s electrical systems to function is often provided by the alternator.

Thus, an inconsistent electric charge may reach various components, including your headlights, if the alternator in your car has a broken relay.

For instance, your headlights might dim as you accelerate, but they might brighten up once again when you bring the car to a stop.

Therefore, this can be a sign of a bad alternator relay.

6. Car Electronics Not Working

Additionally, malfunctioning electrical accessories on your automobile may be an indication that the alternator relay needs to be repaired.

For instance, if the power windows and locks on your automobile stop working, there can be an issue with the alternator relay.

Moreover, the same is also true for the other electrical parts of your automobile, such as the air conditioning system, entertainment system, and accessory ports.

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These problems can therefore assist you in determining if the alternator relay is the cause of the issue.

7. Car Won’t Start Or Stalls

In addition to my points above, the alternator relay may be damaged if your automobile repeatedly stalls or won’t start.

For instance, this would prevent the car from starting because the battery might only be able to supply enough energy to switch on the ignition.

Moreover, the engine can stall if the alternator is unable to provide enough power to the spark plugs sufficiently to keep the engine running.

As a result, your car’s alternator relay may malfunction, causing these problems.

8. Burning Smell From The Engine Bay

In addition, if the alternator relay has gone bad, burning smells could come from the engine bay.

For instance, if it smells like burned wires, it is probably to blame for the alternator overheating or burning.

However, if the air smells like burnt rubber, the alternator belt may have ruptured due to the extreme heat generated by the alternator due to the relay failing to prevent the excess power from reaching it.

Therefore, as soon as you notice any burning smells emanating from your car, it is best to look into the cause.

9. Noises From The Engine Bay

Sometimes, you might not know that there’s something wrong with the alternator until you hear growling or whining noises.

When the alternator is operating as intended, its component elements typically rotate in unison with one another.

Nevertheless, if the alternator has a problem, such as a faulty alternator relay, this could result in unusual and unanticipated grinding noises from parts rotating out of sync with one another.

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As a result, if you hear these noises coming from your car, a faulty alternator relay is probably to blame.

To know more, you can also read our posts on bad alternator pulley symptoms, bad alternator fuse symptoms, and bad alternator diode symptoms


When you suspect the alternator relay is broken, there are a few warning indicators to watch out for, such as a dashboard warning light and odd sounds or odors.

A faulty alternator bearing may also cause considerable harm to the alternator, which could then affect the ignition system.

As such, you should look into replacing the alternator relay as soon as possible.

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