Brake Lights.

Switch off.
Brake lamp circuit and horn circuits are still hot.
Pull the horn fuse for now.
Power comming in the brake light switch and leaves the brake light switch on an off white/beige wire. If that proves when pedal is pressed , stick a hair pin in the connecter so you dont have to hold the pedal down for further testing. Beige wire goes into the signal switch comnnecter at bottom of column. When that switch is in the neutral/centered position you should find same power comming down the column again on a green and a yellow wires, through same connecter and going on toward rear fixtures.