Popping signal fuse on minimal wiring diagram

AAAAAUUGUGHG. Sometimes I really hate my bike. I spent 2 hours setting and wiring in a brake light only to have it not work... which lead to more diagnosis and I realized that every time I flip the key to on I pop my 10A signal fuse. (All fuses are blade type, btw).

I had ridden this bike several times before it started acting up electrically so I'm not sure what the issue is now. When I first went with the minimal wiring diagram I followed it to the T but may have left in an additional piece.

After the 10A signal fuse I have a brown wire that runs to the Rectifier, and another brown wire that runs to the brake light. There is, however, an additional brown wire that runs to a plug with Green/Brown that then runs underneath/into the engine right by the starter. What is this plug?

Either way, I did as much testing as possible with my limited electrical knowledge. I got all the way up to unhooking everything AFTER the fuse, leaving only a single wire lead coming out that terminates to nothing. Still, every time I turned the key, the fuse would blow. What could be going wrong here?

 

If you have everything disconnected, it must be the switch itself.