I'm living in Spain where Red turn signals are illegal so my USA Nightster had to be switched out.

From a previous post I learned the Black is the hot wire, the purple is the turn signal wire & brake light wire, and the blue is the running lights.

But now I want to put a nice Ultra Bright LED panel on the back fender as a break light. From the wiring diagram, the purple is the turn signal/brake light. How do I separate the function.. IE: I want to isolate the break light wire from the turn signal before they are combined to make my brake light function as just a brake light and my turn signals just function as turn signals. ?

Anyone know what color wire is the brake light only? Thanks