I'm having trouble getting a sidemount license plate with brake light to work. I have a Rocker which has two brake/turn lights and a license plate light, all LED. My new light is a dual filament bulb that acts as a brake light, running light, and license plate light. I'm using wiring that was running from one of my old brake lights and am having trouble getting everything to work properly I've tried multiple way of wiring it up and still can't get it to work. I can get a running light but not a brake light, or I can get a brake light and no running light. Every time I can only get the higher amperage filament to light up. This new light has only two wires, one black I'm assuming is a hot, and a green I'm assuming is a ground. I've eliminated the turn signals so that won't be an issue but I just don't know what I'm doing wrong. I was planning on keeping the stock pigtail connector, how I'm wiring it up now, but that can go if needed. I'm just confused and need some help.

 

In the dc side of the electric world black is ground.

 

definitely backwards wiring. I would even go further. If this is a brake / license plate light, there might be no ground at all and it may need to ground via the chassis. Personally I would take it off of the bike, and use a 9volt battery and a couple of wires with alligator clips to figure out how it gets wired.

 

I was just going to say this. I put a tombstone tail light/turn signal on my uncle's old dyna and couldn't figure out why things weren't working when I hooked up both sides...then it hit me.