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How to Replace the Voltage Regulator in a Harley-Davidson

by Gabriel Scofield

A motorcycle charging system is made up by three main components, the alternator, voltage regulator and the battery. The alternator consists of two main components: the rotor which is mounted on the crankshaft, and the stator, which is fastened to the crankcase. The voltage regulator is a series regulator with shunt control. The circuit combines the functions of rectifying and regulating. The voltage regulator is not repairable; it must be replaced if it fails.


Unplug the regulator from the alternator lead; this is beneath the regulator.

Cut the six cable straps and bend back the two metal tabs securing the regulator wire to the frame member.

Remove the battery, battery tray and the seat. Disconnect the regulator wire lead from the main circuit breaker. Remove the remove regulator mounting hardware and the regulator.


Position the regulator at the frame down tubes. Install the mounting hardware.

Route the wire lead along the inside of the bottom frame member; connect it to the main circuit breaker.

Secure the wire to the frame with six cable straps (or zip ties) and two metal frame tabs.

Install the seat, battery and battery tray.

Plug the regulator into the alternator lead.


  • It is a good idea to perform a charging system output test after completion of this job.

Items you will need

About the Author

Gabriel Scofield started writing in 2003 for motorcycle dealership websites. He graduated from the Motorcycle Mechanics Institute with a certificate in Early & Late Model Harley-Davidson. He since has reached the level of Harley-Davidson Master Technician.

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Photo Credits

  • police motorcycle image by Aaron Kohr from