How to Replace the Voltage Regulator in a Harley-Davidson

Written by gabriel scofield
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How to Replace the Voltage Regulator in a Harley-Davidson
Always check for a dead or weak battery before performing any other charging system checks. (police motorcycle image by Aaron Kohr from

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.

Skill level:

Things you need

  • Hex head wrench set
  • Standard wrench set
  • Metal snips
  • 6 cable straps or zip ties

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  1. 1

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

  2. 2

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

  3. 3

    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.

  1. 1

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

  2. 2

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

  3. 3

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

  4. 4

    Install the seat, battery and battery tray.

  5. 5

    Plug the regulator into the alternator lead.

Tips and warnings

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

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