5 SYMPTOMS OF A BAD VOLTAGE REGULATOR

PURPOSE

The purpose of the voltage regulator is to prevent the alternator from undercharging or overcharging the battery. This helps keep your battery charged to start your car. It also prevents battery damage from overcharging. 

location

In most cars, the location of the voltage regulator is either attached to the alternator or inside of it. In older cars with carburetors, it could be found on the firewall. Some newer cars don't have a voltage regulator, instead, the alternator voltage is controlled by the engine control module (ECM). If you're having trouble finding it, here is an excellent car repair manual.

The voltage regulator can fail in two different ways, it can either restrict the correct amount of voltage to charge the battery, or it can send too much voltage to the battery. Both will create different types of symptoms that we’ll talk about today.

symptoms

warning lights

The first symptom of a faulty voltage regulator is having warning lights on. More specifically a battery light will come on. In some situations, these lights may turn on as well:

• SRS

• TCS

• ABS

• BRAKE

discharged battery

The second symptom is a discharged battery. You’ll be trying to turn on your car only to find out it won’t start. This can be caused by the voltage regulator limiting the amount of voltage needed to charge the battery. This results in the battery not having enough power for the starter to crank your engine and start your car. 

dead battery

The third symptom of a faulty voltage regulator is a dead battery. You’ll notice that your battery is needing a replacement before its expiration date. This can happen if the voltage regulator is overcharging the battery. Specifically, anything over 15 volts can damage it.

headlight problems

The fourth symptom of a bad voltage regulator is having headlight problems. You may notice your headlights increase in brightness as you accelerate or on the flip side, you may notice them more dim than usual.

blown fuses

The last symptom you could be experiencing with your car is blown fuses. A bad voltage regulator can cause the alternator to overcharge the battery, therefore, increasing the voltage. According to Ohms's law (voltage/resistance = amperage), as voltage increases, so does amperage, and if amperage exceeds what the fuse is rated for, the fuse will blow.

---

If you concluded that your voltage regulator needs to be replaced and you want to do it yourself, I would recommend getting a repair manual here. You can use code “AD10VA” for 15% off one-year subscriptions for any US Order.

You can also buy a new voltage regulator here.

Check out my YouTube video!

Disclaimer: Some links in this article may be affiliate links.