I have an 08 softail custom and melted the headlamp plug that connects to the bulb. Hint, don't run a hotter bulb, it's brighter but if you ride for many hours in one day it will destroy the plug. Anyway I bought a replacement H4 plug from an auto store that had a yellow, black, and a white wire. The FXSTC has 2 yellow, a black, and a white. I matched the black and the whites and connected the two yellows from the bike to the one yellow on the plug. Now the high works OK but the low beam is very dim.
Does anyone know how to wire this?