Step-by-Step Guide: How to Bypass PCM Voltage Regulator

Is your car stalling while you drive it? The lights and other components may also be flickering. Or worst, is your battery swelled or leaked because of overcharging?

If you’re facing any of these issues, it’s time to pay attention to your vehicle’s voltage regulator. Why? All of the stated nightmares are consequences of a faulty voltage regulator.

However, if you aren’t a gearhead, you must be unfamiliar with what a voltage regulator is. A voltage regulator is a component that stabilizes all the current flowing through your car.

And at times, it may be defective, leaving you stranded on your road trip. In such a case, you should know how to bypass PCM voltage regulator to run it temporarily and reach a nearby mechanic.

Lucky for you that in this article, we’ll be covering just that. We’ll discover an in-depth guide on bypassing a PCM voltage regulator on an alternator. So, let’s jump into it.

How Do You Identify a Faulty Voltage Regulator

Identifying faults in your vehicle’s hardware can be tricky. And that’s why you’re likely to ignore issues with the voltage regulator, even though it can be critical. 

So, how would you know that your voltage regulator is malfunctioning?

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Well, you can easily identify that your vehicle’s voltage regulator is faulty by connecting it to the multimeter. Then, based on the multimeter’s reading, whether it is faulty is decided.

Here are a few tips for testing and identifying a defective voltage regulator.

1. Connect Multimeter

It is important to connect the multimeter correctly to the battery. For this, connect the red wire to the battery’s positive (+) terminal and the black wire to the negative (-) terminal.

After connecting both wires correctly, turn on the multimeter.

2. Start the Engine

Now start the engine so that the voltage reading is displayed on the multimeter’s screen, which is expected to be around 12.4 volts.

3. Increase the Engine Power

Now, slowly increase the engine power and set the car idle to somewhere between 1500 and 2000 RPM to check the voltage regulator.

If the voltage rises above 14 volts, this might be an indication that your car’s voltage regulator is faulty and needs to be replaced.

Note: Replacing the voltage regulator is not a big deal since they are commonly sold. You simply need to buy a new one and take your car to the local mechanic to replace it.

How to Bypass PCM Voltage Regulator on the Alternator

Once you’ve found your voltage regulator faulty, bypass it using an alternator. For this, you’ll need the right tools. Make sure to follow the below step-by-step guide properly to ensure the right process.

Step 1: Locate the Voltage Regulator

Open the front hood of your car and locate the voltage regulator inside it. But ensure your car’s engine is cool down to avoid harm.

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Use protective hand gloves while working with the voltage regulator as a safety precaution.

Step 2: Disconnect the Battery

Block all the sources from the battery to your car’s voltage regulator, and ensure the battery is disconnected.

Don’t forget to remove wires that indicate positive and negative terminals.

Step 3: Search the Voltage Regulator Socket

Identify the position of the voltage socket; mostly, it is located at the side of the car’s computer near the voltage regulator.

It is a rectangular-shaped socket box that contains some wires; once you have found the socket, connect it to the alternator.

Step 4: Find Out the Alternator

It’s time to find the alternator and connect it to the voltage regulator, mostly bolted to the side of your car’s engine.

Step 5: Connect the Alternator

Initially, locate the wires. The blue wire from the alternator should now be connected to the voltage regulator’s bottom post, and the green wire should be connected to the regulator’s top post.

Make sure that you tape any extra wires that are coming out as a safety precaution.

Step 6: Connect a Fuse Box

Now locate the 12-volt switch at the back of the switchboard panel. After finding it, connect the fuse box.

Step 7: Reconnect the Battery

The voltage regulator can now be completely bypassed by connecting the red wire to the battery’s positive terminal and the grounding wire that extends from the alternator to one of the ports on the voltage regulator.


Bypassing the PCM voltage regulator isn’t complicated with the right tools and techniques. Until you have an old vintage-type car with which bypassing is difficult compared to modern cars.

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Although bypassing the voltage regulator might ease the pain, we don’t recommend it. Because the 16-volt charge that the alternator will produce can harm your vehicle.

Therefore, you should only consider bypassing the regulator temporarily. We recommend taking your vehicle to a qualified mechanic for the regulator replacement as soon as possible.

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