Hey everyone, I'm John, this is my first time posting. I've been reducing down the writing on my 02 Harley sportster 1200c and have run into a problem right at the home stretch. I know the red/yellow wire is my run light and the blue is my brake, and I can get them to work but only if the other one isn't on. I can either have just a run light or just a brake light. My after market tail light is wired fine, it's the wires going into my harness under the seat I can't figure out. Thank you

 

I think you have that backwards. Blue is usually the running lights on a Harley. Red/ Yellow the Brake. I just did a quick check for a schematic. I did not see one for a 2002 XL, but here is one for 99-00, and 2003. They have the same wire codes.

http://www.officialharleyparts.com/h...0_xl_1200S.jpg
http://www.officialharleyparts.com/h...3_XL_1200S.jpg

 

There are three wires - that makes only six combinations in which they can be connected. Jus' sayin'! Won't take long to try each of them.....