How to Test the Voltage Regulator in a Chevy Alternator

by Zyon Silket
itstillruns article image
orange and black image by John Sfondilias from

The voltage regulator is built into the alternator on all Chevys made from the 1980s to at least 2010. Simply put, the regulator restricts the amount of voltage being sent to the battery. Without a regulator the battery would receive upwards of 30-volts of power while charging, which would quickly damage or destroy your battery. When your Chevy is running, you should get approximately 12.8 to 14.0 volts of power, and there is a quick and easy test to determine if your regulator is over- or under-performing.

Step 1

Place the red lead of you multimeter onto the positive battery terminal on your car battery. Place the black lead of the multimeter onto your negative battery terminal.

Step 2

Place the multimeter onto 20V DC and measure the output. The battery should have at least 12.0-volts of power with the vehicle off. If it does not, charge the battery until it measures 12.0-volts. Without a properly charged battery, you cannot accurately measure the voltage output of the regulator. When the battery measures at least 12.0-volts, move to the next step.

Step 3

Tell the second person to start the automobile while you watch the output of your multimeter. If the multimeter shows less than the previous reading, the regulator is defective and you are risk of damaging your battery because it is not getting enough power to stay charged. If the battery reads more than 14.0-volts, the regulator is not limiting the power being transferred from the alternator to the regulator. If this is the case, it is also defective. If the multimeter stays between 12.8-volts and 14.0-volts, the regulator is working properly.

More Articles

article divider