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HOWTO Wire an Accessory Circuit and Light Kill Switches

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The accessory circuit is run from the battery to a relay. I then wire my Dual Star heated grips to the relay. Lastly, I break the headlight and tail light circuit and wire a switch between each.

From searching here I found most consider it proper to put accessories on a separate, fused circuit run from the battery. This involves the use of a relay to switch power on only when the bike is on. The relay scared me away, but I found it is really quite easy, let me show you how. I will hopefully save you from repeating my mistakes.

***Click Thumbnails to View Complete Pictures***

Parts List

  • (2) 20amp weatherproof SPST switches- Only if you are wiring the light kill switches. I got mine from Action-electronics.com, part #35-3500.
Linky(1) 12VDC Automotive Relay 30A- I bought mine from Advanced AutoParts for $4.00. I see them on Amazon for a bit over one dollar. Linky
(1) Fuse holder- I'm running a 7 amp blade fuse for my grip heaters only, no problem. It is part of my battery tender hookup.
(20') 12-14awg wire- I ran heavier gauge for the accessory circuit and 14awg for the lights, 20ft should be enough and 14awg would probably be suitable all around.
(10) 1/4" Female Quick Connect Blade Terminals to fit your chosen gauge wire- The relay requires 4 and the kill switches require 6 if they have LED indicators, 4 otherwise.
(2) Ring terminals to fit battery posts- not sure of the exact size, 1/4" might work well, I used my battery tender hookup, they are 3/8" I think.
(1) Tap-Splice Connector- Included with my heated grips, also called quick-splice

Tools and Other Supplies

  • Soldering Iron
  • Solder
  • Wire Stripper/Cutter
  • Crimper
  • Dielectric Grease- Use on all terminal connections
  • Electrical Tape- Wrap solder joints with this
  • Double Sided Tape
  • Zip ties

The Accessory Circuit to Relay

I hooked mine up to the battery a little special, let me explain. I bought a Battery Tender Jr. and had already wired a set of leads to the battery. It is fused and takes up a lot of room behind the side panel, I didn't want to try and add another fused connection to the battery. The battery tender came with a second set of leads with alligator clips. I got the idea to connect these leads to the battery leads and cut the clips off the end. I then soldered lengths of wire and ran them along the frame following the stock harness, but I did not tear the harness out and unwrap to include my new wires.

When plugged in to each other the wire with the red alligator clip actually becomes the negative and vice-versa:


If you don't have a Battery Tender, or dislike the idea, then you will need to crimp ring terminals to the wires for attachment to the battery, ensuring the fuse holder is wired in-line with the positive circuit.

Wiring the Relay

So now you have your battery leads routed to the front. Go ahead and crimp a female quick connect terminal on each. (NOTE: I crimped another, smaller wire into the negative terminal so I could ground my accessories to it rather than the frame.) Connect the positive lead to pin 30 on the relay, the negative lead to pin 85. Now we have two more pins to connect. Pin 86 is wired to a switched power source. I chose the orange wire from the ignition cylinder. I tapped into it using the tap-splice connector and short length of yellow wire included with my Dual Star heated grips. The yellow ignition lead then connects to pin 86. Lastly, crimp a female quick connect terminal to two short lengths of wire. These wires will connect the power output of the relay, pin 87, to your accessories power input, in my case, the Dual Star heated grip hi/lo switch and tail light switch LED.

Notice the smaller wire crimped onto the negative lead, I will ground my accessories to this:


I cut the sheathing back a little to further expose the wires coming from the ignition switch. I then used a tap-splice connector to feed the relay a switched power source:

ignition_tap01_tn.jpg ignition_tap02_tn.jpg

I mounted the relay to the side of the headlight bracket with double-sided tape. It didn't want to stay flush so I secured it with a zip tie:

relay_wired_tn.jpg relay_mounted_tn.jpg

Wiring the Dual Star Heated Grips

The grip heaters have 3 wires each: high (white), low (blue) and ground (red). Remember the wire I crimped to the negative battery cable earlier? I'll take care of the two red wires by connecting them to this negative lead. (NOTE: If you're going to kill the headlight with an LED switch you'll want to solder a short lead here to ground the LED.)

Here there should be three wires grounded to the negative battery lead, the two grip heater grounds, and the headlight LED ground. The white wire needs a positive source:


The Dual Star kit came with a 3-pin Hi/Off/Lo switch. The middle pin will connect to the wire lead we ran from pin 87 on the relay. That leaves two sets of high and low wires, simply connect the highs to one pin and the lows to another. The two wires plug into one pin using the piggyback connectors included in the kit. Their instructions show the high wires going to the low pin on the switch and vice-versa. It doesn't really matter as you can rotate the labeled faceplate on their switch. I just rotated the switch so pushing forward was high and backwards was low:

grip_heater_switch01_tn.jpg grip_heater_switch02_tn.jpg

I bundled the wire together neatly by wrapping them a good length with electrical tape. I have plenty of room to reposition the switch later or let the headlight shroud rest on the fender while I'm working without having to remove the switch from the shroud each time.

The clutch-side heater's wiring was easy to route, following the handlebar switches' wiring. The throttle-side was a little trickier, I just followed the throttle cables and zip tied in a few strategic places to allow the wire to move freely when the throttle is turned:

clutch_side_wires_tn.jpg throttle_side_wires_tn.jpg

Headlight Kill Switch

There's several ways to do it, I chose to break the white power wire for the low beam. This will allow me to have the headlight switched off but use the handlebar switch to turn the brights on quickly should I need to. I broke the white power wire as it comes out of the dimmer switch. I soldered leads to each end and crimped female quick connect terminals to the other end of the leads, which then connect to pins 2 and 3 on the switch, or the two close together. The pin off by itself on the end is pin 7, which you have to a ground if you want the LED to light up. If you installed the accessory circuit too, this is why we left a lead available from the negative battery above.

We break the white power wire for the headlight low beam, it looks like there is a second white wire beneath it in this photo, but it is in fact a black wire with white stripe:

headlight_cut_tn.jpg wiring_complete_tn.jpg

Tail Light Kill Switch

Killing the tail light is a little more complicated if you want the brake light off too. You have to run wires from the tail light ground under the seat by the rear fender up to the kill switch. I had already cut my stock connector to accompany my EDGE tail light. What I did was break the black/white ground connection and soldered a wire lead to each. Which I then ran through the frame following the stock harness up to the headlight shroud. This means the connector is pointless, yes, but for some reason I'd like to keep the main harness untouched. The only reason to disconnect it that I can see is if I should need to replace the tail light, which I'll have to desolder anyways.


Now that the wires are up front, cut to length and crimp on the female quick connect terminals, connecting them to pins 2 and 3. Now to light the LED, pin 7 will need to be ran to a positive since we broke the ground on this circuit. If you wired the accessory circuit, you should have an extra lead running from pin 87 on the relay.

And here's the finished product, plenty of wire room to relocate the switches when I work on a dash, but this will do for now:

finished_view_on_tn.jpg finished_view_off_tn.jpg

I will likely add a GPS unit in the future, all I would need to do to hardwire it is connect another set of leads to the pin 87 positive wire and pin 85 battery ground. I read that some prefer their GPS always-on, but I figured if I'm only making a quick stop then I should be able to leave the bike switched on and the lights off without draining the battery too much.

A Few Soldering Tips

  • Let the iron heat up completely, at least 5 minutes.
  • Use twist ties and alligator clips to hold the wires in place and together while you solder.
  • Solder one side, let cool for about 15 seconds before turning over, and make sure you secure the wires again before starting.
  • Touch the soldering iron to the wire itself, at about a 45 degree angle. Then touch the solder to the crevice between the iron and the wire. Move the iron and solder together up and down the wire. You want the solder to soak into the wire strands, not pearl up on the surface.

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yes props to you for doing the write this sort of info is so good when you are a nub like me and trying to do something you havent done before.

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Yea this is a great write up!!!

Love the pics to go along. I'm a newb and just installed the edge tail light and blinkers. I just kind of figured it out as i went along, but i really wanted to put a relay in to fix the fast blinking.

This will be most useful:applause:

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Hi ppar,

Just wanted to inform you that a different relay is required for slowing down the blink rate with LEDs. They are called IC relays and Forest sells them; however, it doesn't seem like people have had much luck wiring them correctly. I'm not sure how they work, but I found that people are using an electronic flasher instead. Check out this thread with a picture write-up, DRC in line resistors, or IC relay?? Help!!.

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I had no problem setting up the DRC IC relay. Many here have used other less expensive variations with great results. Pretty much any electronic fasher that is load independant will work. It will have either two or three wires, the third wire is a ground.

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