How to Use an Ohm Meter to Check a Voltage Regulator

by Tamara RunzelUpdated March 09, 2023
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dead battery image by Katrina Miller from

Items you will need

  • Ohm meter

  • Two people

You can check your vehicle’s charging system yourself at home with an ohm meter. An ohm meter, also sometimes called a multimeter, is relatively affordable at hardware or auto parts stores. The appliance measures how much resistance there is in a wire compared to the charge going through the wire. The alternator and voltage regulator make up the charging system of your vehicle. The voltage regulator maintains the voltage from the battery while the vehicle is running. If you have dim headlights or other abnormal electrical issues with your vehicle, you should test the voltage regulator.

Please find our YouTube video to help:

1. Turn the dial on your ohm meter to no less than 20V DC.

Turn the dial on your ohm meter to no less than 20V DC.

Updated from a helpful reader:‌ In the article, it states to set your multimeter to ohms. However it needs to be set to no less than 20V DC or if equipped AUTO DC.

The ohm symbol looks similar to the symbol for the Greek Omega.

2. Start your vehicle.

Start your vehicle. Make sure the car is in park and the parking brake is set.

3. Open your hood

Open the hood of your vehicle so you can access the battery.

4. Attach Ohm Meter to Battery Terminal

Touch the black meter lead of your ohm meter to the negative battery terminal and the red meter lead to the positive terminal.

5. Display should run between 13.8 and 14.5 volts.

Check the display to see how many volts are running through. It should run between 13.8 and 14.5 volts.

6. Step on the gas to rev the engine and check the reading

Step on the gas to rev the engine and check the reading. It should go up and then settle back down to the previous reading. You will probably need another person to read the ohm meter or step on the gas.

Know if Your Battery is Dying:

If the ohm meter shows a reading much below 13.8 volts, your battery is probably dying and the alternator may not be working properly. If it shows a reading about 14.5 volts, your voltage regulator is probably faulty.

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