Six Signs That Your Voltage Regulator Is Not Working (& Their Replacement Cost)

There are tons of components in your vehicle’s charging system. While the alternator and battery get the most attention, the voltage regulator is just as important.

But if you’ve never heard of a voltage regulator or don’t know how they work, you run yourself in circles trying to figure out what’s wrong with your vehicle.

In this comprehensive guide, we’ll break down everything you need to know to check your voltage regulator and get your vehicle back on the road running like new!

Bad voltage regulators are most commonly accompanied by a stalling motor and warning lights on the dashboard. This can cause your vehicle's electrical components to be damaged by the spiked voltage. You may also see flickering lights at night.

A voltage regulator may be required to prevent your vehicle from experiencing a variety of symptoms.

The following is a detailed listing of six symptoms that indicate a poor voltage regulator.

Bad voltage regulator symptoms

1. The Battery is too high in Voltage

A voltage regulator may fail in one of two ways. It can cut off the voltage regulator's ability to supply enough power to the battery. It can also direct excessive power to the battery. If it’s sending too much power, you’re going to run into problems sooner rather than later.

A fully charged battery has 12.6-volts, but it’s not uncommon for them to sit at 13.7 volts while the alternator charges them. You can endanger your battery by charging it more than necessary. You’ll notice the battery is getting far too warm, potentially warping, and if left alone long enough, potentially cracking or exploding.

2. Dead Battery

You’ll get too much voltage if the voltage regulator isn’t diverting power when it should. If it’s not sending enough voltage to the battery, it will constantly be dead.

It can be one of the more frustrating components to troubleshoot because you don’t usually start looking at your voltage regulator when your vehicle isn’t starting as it should.

You can easily measure the charging voltage at the alternator by using a multimeter.

Related: Alternator Not Charging – 6 Causes & Diagnostics

3. Battery light or check engine light

Whether your voltage regulator is neglecting to charge your battery or it’s overcharging it, various sensors might pop either a check engine light or a battery light. It is a sign that your car should be stopped immediately if you see one of these light flashing.

You might lose your car completely or you might have the battery explode. There is no way to be happy about it.

4. Electrical Components not operating in a consistent manner

The voltage regulator will be intermittently operating, which can cause electrical components in your car to malfunction. Whether it’s your radio, dashboard lights, or more critical components like your fuel pump, you’ll notice inconsistent operation.

You may have unusual electrical problems that are not related to the regulator.

5. Vehicle running while in use

If your voltage regulator isn’t directing enough power to the battery while the engine is running, your vehicle will shut off as you’re driving down the road.

Your vehicle needs voltage to run, so if it’s not getting any, you’re going to run into problems. This problem will usually be resolved by replacing the alternator or voltage regulator.

Similar: Six Reasons Your Car Shuts off While You Drive

6. Lamps that dimming/pulse

If your vehicle’s voltage regulator is working inconsistently, then you might notice that your lights are “pulsing” as they get brighter and dimmer. This happens when your voltage regulator is unable to maintain a consistent voltage like it’s supposed to.

However, if your voltage regulator is starting to fail and does not maintain the proper amount of voltage, you might notice that you have lights that aren’t as bright as they should be.

Voltage regulator function

Your voltage regulator controls your voltage, even though it may sound redundant. If that doesn’t make sense, keep reading, and we’ll break down exactly how it does it.

All of the voltage starts in your alternator, but since it’s belt-driven, it’s creating voltage whenever your engine is running. Your battery is only capable of handling 14.5 volts per hour (12.6-volts for a fully charged charge). It would explode if the alternator continued to dump all of that voltage into your battery!

Your voltage regulator monitors your battery’s current-voltage and sends voltage that way when it starts to dip too low. The regulator will divert excess voltage to ground when the battery is sufficiently charged, which effectively eliminates it from your system.

When everything is working correctly, it’s an extremely efficient system that keeps everything working the way it should.

Locate the Voltage Regulator

Most of the time, the voltage regulator is located on the alternator’s back or inside the alternator.

The voltage regulator can be found on some vehicles, though it's very uncommon.

Depending on which type of alternator you have, the location of the voltage regulator inside your alternator can make it difficult to find. They may be placed in obvious locations or buried by others.

The final twist is that many vehicles with higher horsepower are now incorporating the voltage regulator directly in the Engine Control Module. It runs off a separate circuit in these systems, and you can’t replace just the voltage regulator.

Prices for replacing a voltage regulator

The cost of replacing a voltage regulator is on average between $70 to $400 depending on your car's make and model. The cost of a voltage regulator is $20-200, and labor costs between $50-50.

Removing the voltage regulator depends on the vehicle that you drive. It could mean either replacing the whole alternator, or the regulator.

If you need to replace the entire alternator, it usually costs between $200 and $500 for the part alone. From there, it’s usually a pretty easy job for a mechanic, so you can expect to spend between $50 and $100 in labor.

A Voltage regulator typically costs between $20 and $200. While it’s a big price range, they usually cost a little less if you drive a smaller vehicle. The accessibility of the regulator can also affect how much labor costs.

Because of their varying locations, voltage regulators can cost as little as $50 for labor, but for some vehicles, it’s possible to spend closer to $200.

If you’re mechanically inclined, you can replace both an alternator with a voltage regulator and a standalone voltage regulator without too much of a hassle.