HOW TO DIAGNOSE A BAD VOLTAGE REGULATOR? -

The alternator (with the voltage regulator) provides all of the electric power for your car and recharges the battery while driving.

When the voltage regulator fails, the alternator is practically useless.

This video will show you how to find out if the voltage regulator is causing the problem or if it’s something else.

Besides this website, you can also watch videos on our YouTube channel, where we have many car-related videos that may help with maintenance, driving, etc.

WHAT IS A VOLTAGE REGULATOR?

The voltage regulator controls and regulates the voltage output from the alternator.

A stable voltage is necessary to recharge the battery and keep all the appliances, electric and electronic, working properly.

Without it, every time you rev up the engine, the voltage would go higher; when the engine idles, it would be lower.

In both cases, the battery would not recharge properly, and the electrics and electronics would be damaged.

It keeps the voltage at a stable 14 volts on cars, and on trucks it’s 24 volts.

For more information about alternator problems, click here.

THE SYMPTOMS OF A BAD VOLTAGE REGULATOR

The most common symptoms of this problem are:

-A blinking battery warning light.

-There is no warning light at all when you turn on the ignition.

-The car battery is constantly drained, even if you recharge it or buy a new one.

-You may sense a sulphuric smell coming from the car’s battery and engine bay.

Three main things cause problems on a voltage regulator: those are worn-out brushes, faulty electronics, and bad electrical contacts to the regulator and to the alternator.

The moment you notice any of the mentioned symptoms, do the next things we’ll show you.

HOW TO DIAGNOSE A BAD VOLTAGE REGULATOR

For diagnosing, you’ll need a multimeter.

With cars, set it to a range higher than 14 volts.

Stick the red probe onto the positive battery terminal and the black probe onto the negative terminal.

Next, start the engine and let it idle.

This is the key part for diagnostics: if the voltage is slightly lower than 14 volts, like 13.2 or 13.5, it may be the voltage regulator.

But it’s not that certain since other things, in this case, may be causing the problem. Like the stator, the rectifier, a loose serpentine belt, or a bad electrical connection.

Nevertheless, the voltage regulator is the first part to check.

If the voltage is higher, like 15 or even 16 volts, 99 percent it’s the voltage regulator. Even if you turned on the lights, the voltage would be almost the same.

With most cars, the sure sign that the voltage regulator is faulty is that there is no battery warning light and there is a high alternator voltage.

Besides this, there is a strong sulphuric smell from the battery since it is overcharged, and the acid is boiling.

The sulphuric smell usually comes after a longer period of overcharging, and if you neglect the problem.

One more way to do this is to use an OBD scan tool and get an error code (if there is one). But from my personal experience, the easiest and most precise method is with the multimeter.

CONCLUSION

The moment you notice any of the problems we’ve shown you, react and inspect what’s wrong.

If you neglect it, you may damage the alternator (namely the stator), the car’s battery, and even worse, the car’s electronics, ECU, and else.

All of these problems are expensive to replace or repair. On the other hand, voltage regulators are, in most cases, cheap, so replace them as soon as possible.