How to Install a Turn Relay Switch on a Motorcycle


Motorcycle turn signals use a relay to flash the signals on a constant basis. Although these relays are quite durable, they do wear out over time. One sign is a constantly illuminated turn signal. Replacing and installing a new turn signal relay is one of the easier electrical tasks that a motorcyclist may have to undertake, but it does require some familiarity with a motorcycle's electrical system.

Things You'll Need

  • Turn signal relay
  • Cable ties or bracket
  • Weather-proof electrical spade connectors

Replacing Stock Relays

  • Locate the motorcycle's turn signal relay. Most motorcycles mount the relay near its battery or electronic control module, located under the seat or behind a frame-mounted side cover. Older machines may use a round, two-pronged relay, while newer machines are often equipped with a rectangular, three-pronged relay.

  • Disconnect the turn signal relay from the motorcycle's wiring harness, pulling the wiring connectors off of the relay's prongs or unplugging it from the motorcycle's electronic control module. Install a new turn signal relay into the wiring harness or electronic control module.

  • Turn the motorcycle's ignition switch to the "ON" position and test the turn signals for proper operation. If the turn signals do not operate properly or only one side illuminates, check that the relay is properly installed and that the turn signal bulbs are in working condition. Turn the ignition switch to the "OFF" position.

Custom Applications

  • Select a suitable location to install the turn signal relay on your motorcycle. Ideally, this area should be easily accessible and within reach of your motorcycle's battery and electrical wiring harness. Install the relay using cable ties or a bracket.

  • Identify the turn signal relay's prongs. The first prong on the right side of the relay is typically used to connect to the motorcycle's main power line from the battery. The second prong at the top center of the relay connects to the turn signal switch on the handle bar, while the remaining prong on the left connects to the motorcycle's ground wire.

  • Connect the appropriate wiring to the connectors using weather-proof electrical spade connectors. Turn the motorcycle's ignition switch to the "ON" position and test the turn signals for proper operation. Check that the turn signal relay is connected properly and that all turn signal bulbs are in working condition if the turn signals do not work properly. Turn the ignition switch to the "OFF" position.

Tips & Warnings

  • An electronic turn signal relay with a minimum amperage of 0.1A is required if you plan on using LED turn signals on your motorcycle.

Related Searches


  • "The Professional Motorcycle Repair Program"; Professional Career Development Institute; 1995
  • Photo Credit reflection of a sports motorcycle image by terex from
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