hydraulic brake controller wiring?

[Wrench]

Hey, I've got the old style hydraulic brake controller that works really well, and I want to keep using it--but I can't find wiring info. It has the brake line from the M/C, and three wires-black, red, and blue. I figure the blue is power to the brakes, how does the rest work? Hot from batt., hot to trailer, ground?

Dumb question I know, but I want to do it right the first time i.e. solder connections, fuse properly, etc.

 

[Russell]

Little bit late here, but black = ground, red = battery power through a circuit breaker, blue goes straight back to the trailer