So after 6 weeks of waiting on the dealership I finally get my bike back only to discover the side mount license plate I have they couldn't get to fit due to my swing arm design. The plate mount has a brake light above it. It has a single double filament bulb that acts as the running light, brake light, and license plate light. It has two wires one black one green. I snipped the wiring from one of my old brake/running lights and temporarily spliced it together with the wiring from the new brake light. I then went through and inserted the pins into the rear pigtail connector. I experimented with both wires attached to various connectors and with one wire grounded on the frame. I could manage to get one filament to light up either as a running light or a brake light but I couldn't get both to work like it should, one being a running light and then the brake light coming on on the second filament. My stock wiring is a slightly lighter gauge than the wiring for the new light, not sure if that matters. This is probably easier than I'm making it out but I'm stuck and just at the point to where I want to get back to riding. If anybody has any help they can suggest I'd greatly appreciate it. If I haven't explained everything clearly just let me know and I'll do my best to elaborate. I can also send you pictures of whatever may help you if you need as well. My email is daveclendenen@yahoo.com.

Also, my bike is an 2009 Rocker FXCW.

 

If you only have two wires, it may ground through the physical frame connection.
Try clipping a wire from the plate bracket to the frame, then connect one of the wires to power, then the other.

 

It has a single double filament bulb that acts as the running light, brake light, and license plate light.

??? With only 2 wires for a double filament bulb the light is self grounding, metal to metal. making 1 wire running/plate light, the other one's for brake light. Are you sure it's duel filament? If your sure, take a positive 12 volt source, and touch each wire the brighter illumination is the brake wire. Which I'm sure you know.