If the high mount brake light is working, it could be a fault with the multi-function switch.

If the high mount break light is not working, at brake switch check for battery voltage at the Light Green/Red wire. If battery voltag is available, depress the brake pedal and test the Dark Green wire for battery voltage. If voltage is available, test the voltage at fuse # 39 (10 A) in junction box at left side of dash. If fuse is ok, test the Light Green wire to multifunction switch for battery voltage when brake pedal is depressed.