When the Brake pedal is depressed it closes the switch and sends the 12v power to the turn signal / hazard switch which the distributes the signal depending on the TS Hazard switch position.
First thing is to test the BL switch. Then follow the power through the column connector to the T/S switch. If the power is getting there next likely culprit is the T/S or hazard switch itself.

Once you have verified the Brake switch power at the switch, you can jumper it to the brown and green wires which are the output to the high filaments or Brake lights. MAKE SURE THE T/S switch is in the CENTER POSITION AND THAT THE HAZARD switch is OFF