Do you have a copy of the service manual? If you google "roadstar service manual" the first item will be a 12 MB pdf of your service manual. Chapter 7 covers electrical fairly in depth.
It looks like the circuit flows fuse->relay->switch->lights->ground. The service manual will give you the complete circuit. The plugs for reading the circuit look like they are both in the headlamp assembly.
If the problem is only when activating one side and not the other, a likely area would be a loose/broken or chaffed wire grounded out. Otherwise the switch or the relay could be shorted to ground. There's not much to the circuit if you take a moment or two to peruse chapter 7.
2013 V Star 1300 Deluxe
OEM Tall Sissy Bar
Memphis Shades Fork Deflectors
Bridgestone Exedra Max Belted Tires
Baron's RSTD 7308 bar