If your car stalls, the lights dim, or its battery dies out suddenly, the most likely culprit is a defective voltage regulator.
Understanding how to bypass the voltage regulator on an alternator can help you in dealing with a faulty voltage regulator.
For this, you’ll need an external voltage regulator, through which the electricity will be bypassed.
A bad voltage regulator could pass excess or insufficient electricity to electrical components. This could lead to damaged parts, so you should get it diagnosed as quickly as possible.
That being said, let’s get started!
How Do You Test a Voltage Regulator?
Before bypassing your voltage regulator, you should ascertain if you need to do it by testing it. The steps for testing a regulator are as follows –
Connect the Multimeter to the Car’s Battery
The first step is to connect the multimeter to the car’s battery.
To do this, attach the multimeter’s positive wire (usually red in color) to the positive (+) terminal of the battery.
And then, attach the negative wire (usually black) to the battery’s negative (-) terminal.
Once you’re done, turn on the multimeter and set it to Voltage DC mode.
Switch On the Car’s Engine
After the multimeter is connected, you will have to start the engine and observe the readings on the multimeter.
The reading should be around 12.6 volts when the engine is idle.
Increase the Engine’s RPM
Now, you’ll have to apply throttle to increase the engine’s RPM. While doing so, observe the multimeter readings.
If the voltage increases and goes beyond 13.5 volts, it indicates a faulty voltage regulator that needs to be replaced.
How to Bypass Voltage Regulator on an Alternator – Step-by-step Guide
Knowing how to bypass the PCM voltage regulator could save you from getting stranded in the middle of nowhere! If you’re certain that the voltage regulator is malfunctioning, you can bypass the voltage regulator.
For this, you’ll need a regulator plug harness, extra wires, and an external voltage regulator.
Here’s the step-by-step guide to bypassing a voltage regulator –
Disconnect the Car’s Battery
The first step is to block power from going to the voltage regulator.
You’ll have to disconnect the car’s battery by removing the connections from both the positive and negative terminals of the battery.
Connect the Alternator to the Harness
There are 3 wires from the harness that we’ll need, 2 of which have to be connected to the alternator.
Locate the wire (usually blue in color) with an ‘F’ inscription on it and connect it to the alternator. Next, connect the white/green wire to the alternator’s plug.
The 3rd wire should be red with an ‘A’ inscription on it. Connect this wire to the positive terminal of the car’s battery.
Mount the External Voltage Regulator
Now, you’ll have to mount the external voltage regulator with bolt screws, preferably on the inner fender or the firewall.
For grounding the voltage regulator, use a metal sheet screw.
Locate the Voltage Regulator Socket
The voltage regulator socket of a car is usually situated with the car’s computer panel or anywhere close to the voltage regulator. It is a rectangular-shaped socket with wires.
Once you’ve located it, connect the alternator’s blue wire to the bottom post of the voltage regulator.
Next, you’ll have to connect the green wire from the alternator to the top post of the voltage regulator.
Connect the Voltage Regulator Switch to the Fuse Box
Locate the 12V key switch behind the switchboard panel and hook a fuse into the bottom slot of the panel.
Reconnect the Battery
Connect the battery’s positive terminal to the red wire and the grounding wire from the alternator regulator to the external voltage regulator.
Once done, you have successfully bypassed the voltage regulator.
Signs of a Faulty Voltage Regulator
The electricals within a vehicle can start malfunctioning for various reasons, but certain signs indicate a faulty voltage regulator.
The most common signs are –
A defective voltage regulator can damage the car’s battery as it may not receive sufficient charging voltage, or it could be overcharged due to excessive charging voltage.
Inconsistent Engine Performance
If your car’s engine sputters, stalls, or doesn’t accelerate without jerking, it could indicate a bad voltage regulator.
The most common sign of a faulty voltage regulator is flickering or dimming lights. It’ll affect headlights, backlights, and interior lights as well.
Instrument cluster malfunctioning
The instrument cluster of a vehicle is home to various meters, gauges, and indicators. If the instrument cluster is flickering or acting erratic, it indicates a faulty voltage regulator.
Frequently Asked Questions
1. Can a regulator be bypassed?
Yes, it is done to prevent power disruptions when installing/replacing a regulator.
2. Can you adjust the voltage regulator on the alternator?
Yes, it is possible to adjust the voltage regulator on an alternator. Although this varies across vehicles, most older models have a manually adjustable voltage on their regulators. Usually, it can be changed with a screwdriver.
3. How do I know if my voltage regulator is bad?
The most common indication of a faulty voltage regulator is flickering or dimming car lights. Since the voltage regulator is responsible for supplying constant power to the lights, a faulty regulator will lead to the lights not functioning properly.
4. Can a bad voltage regulator destroy the alternator?
In cases where the defective voltage regulator isn’t replaced in time, the alternator and other electrical components on the car’s engine are prone to severe damage. Therefore, a faulty voltage regulator could actually destroy an alternator.
5. Will a bad voltage regulator drain your battery?
A faulty voltage regulator may drain your battery, overcharge it, and even damage it permanently. If you’ve noticed signs of a defective voltage regulator, you should get it fixed as soon as possible.
With all of that being said, you should now know how to bypass the voltage regulator on an alternator.
Since electrical components are sensitive, you should always be aware if your cars are giving off signs of a faulty voltage regulator.
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