How do you test for a bad voltage regulator?

Answer by  mechtech74 (692)

Short answer: bypass the regulator and measure whether your charging output increases to over 14 volts. Do not leave the bypass on when done or it will drain the battery.

Answer by  mike50 (53)

Attach volt meter clamps to the output leads of the voltage regulator. Slowly fluctuate the input voltage to the regulator by accelerating the alternator or electric generator. If the regulator is good the output voltage will stay within voltage range specified by manufacturer.