Just chopped the fender off my 07 Sportster and installed a new LED tail light (tail and brake light only - no indicators). The new light comes with three wires - black (ground), yellow (tail light) and red (stop light).

I have a repair manual and worked out the rear lighting harness as follows:
BK - ground
V - left turn signal
R/Y - brake light
BE - tail light
BN - right turn signal
O/W - brake light

I removed the stock tail light, cut the connector off and wired it all up directly. The indicators work OK but the tail/brake light gives me trouble.

The light comes on when I switch on the ignition but I am not sure if it's the tail light or the brakes that light up. The problem is, nothing changes when I pull either of the brakes.

What puzzles me is the two cables in the harness for the brakes - both R/Y and O/W are shown in the wiring diagram as going to the tail light bulb - why two wires?? I hooked up both to the the red wire of my new LED light and then hooked them up separately - I always get the same result.

So in short, how do I hook up the four harness wires for the stock tail light (BK, BE, R/Y, O/W) to the three wires of my LED tail light??

Thanks!

 

Red/Yellow wire is the brake light wire.

The Orange/White wire is an accessory wire that runs all over the bike and powers up the brake lights by running to the brake switches.
When the brake switch is activated it completes the circuit and sends power up the Red/Yellow wire to light up the globe.

So leave the orange/white wire out of the equation.

You need to work out which of your 3 wires are brake / earth / tail light

Since you hooked it up wrong I would check the fuses as you might have blown one.

 

I removed the O/W wire and it works! Thank you!!

 

I have an 07 sporty 1200L and I am trying to install an aftermarket taillight assembly. I have gotten all my turn signals and running lights to works as they should but I can't get my brake light to work. I have looked at the wiring schematic and wired it the way I feel it should be ran. My taillight/brake light only has two wires not three and it has a dual filament bulb. I spliced the blue wire and the red/yellow wire together and then connected them to the hot wire on the taillight and all I'm getting is the running light. All help is appreciated.