Switched 12V Power for ZX-6R


I am not a mechanic or a representative of any motorcycle or tool manufacturer or anything else official. This page is only my notes on doing this procedure myself. Although I believe what I have documented here is correct, I make no promises and you do this at your own risk.


I added a few electrical accessories to the bike, but wanted them powered by 12 volts that is on only when the ignition is on. (I knew I would forget to turn them off, draining the battery if they were directly connected.) This project installs a 12-volt automotive relay in the bike to provide power that is switched by the ignition.


Tools Required

  • Rear stand (recommended)
  • 4mm Hex Wrench (Allen Key)
  • 12-volt automotive relay
  • Stainless screw, nut, and lock-washer to fit the relay mounting lug
  • Drill and drill bit to fit the above mounting screw (or find a better place for the relay)
  • Fine wire (18 gauge) for control signal
  • Heavy wire (12 gauge) for switched battery current
  • Crimp-on spade connectors for relay contacts
  • Crimp-on lug connector for ground wire
  • Wire cutters
  • Sharp knife
  • Electrical tape
  • Zip ties
  • Soldering Iron and Solder
  • Volt meter

Difficulties & Warnings

Easy. Requires comfort with basic electrical circuits and soldering.


Most bike maintenance is easier if you support the bike on a swing-arm stand so it is held vertical. This is optional, but a good investment if you plan to do any kind of work on the bike.

I purchased a 12-volt automotive relay from a local auto parts store. This can switch 12V at up to 30 amps, and requires only a few milliamps on the coil circuit to close the relay.

I played with it in the house, with a volt meter and power supply, to be sure I understood what the connectors did, and labeled it with a silver felt pen on each side to make the connections easy to read in cramped spaces.

I removed the seat from the bike, and looked for a good place to mount the relay.

The first place I picked — on the gas-tank mounting screw (shown in red here) — seemed great until I later realized that, in this location, the relay blocked access to the seat retaining screw, so there was no way to put the seat back on.

So, I decided to mount it in the clear space on the floor of the wiring closet — the area shown circled in yellow here.

I drilled through the floor of this plastic container and mounted the relay with a stainless screw. Under the bike the screw is held by a lock washer, lock-nut, and loc-tite (I really didn’t want it coming off).
Now, we need a control voltage that is on when the bike is running and off when it is not. The tail light seemed a good place to get such a signal, so I removed the rest of the rear covering to make access to the wiring easier.

I unplugged the tail light socket and used a volt meter to discover the function of the 3 connectors (ground, tail light, and brake light), and labeled them with a silver felt pen on the connector. (The centre wire was the tail light signal.)

Then I carefully spliced a wire onto the tail-light wire by baring a portion of the tail-light wire wire without cutting it, wrapping my new wire on the bare spot, soldering, and taping. My new signal wire is blue, and is visible here, circled in red. I ran this back through the body to the location of the relay, and crimped & soldered an appropriate spade connector on the relay end.
Here the blue signal wire can be seen connected to the relay. The relay control also needs a ground source, so I ran a wire (green, circled here) from a nearby frame screw, after confirming, with the volt meter, that it is a source of ground, to the control ground lug on the relay. I crimped a spade connector on the relay end of this wire, and a round lug connector on the frame-screw end, and soldered both.

That’s it. Now, any time the tail light is on, the relay control is powered, turning on the switched relay lugs.

So, the two lugs on the relay that are visible here with no wire on them are switched together when the bike is running, and are disconnected when it is not.

I ran a heavy wire from the +ve terminal of the battery to one of these lugs (but forgot to take a photo). The other lug is now a source of direct battery current, switched by the bike ignition, and suitable for wiring accessories. I’ve used this for a GPS, heated grips, and a heated vest.

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