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.

 

We'll one wire from your light goes to running, one to brake, the missing wire will be to ground. Newer hds have a ground wire to all accessories it is the black wire.