A transmission selector mechanism (16) in a vehicle (10) having a transmission (20), a braking system (14), and a gear selector mechanism (22) is used to prevent the transmission selector mechanism (16) from moving out of a Park position (24) unless a brake pedal (18) has been depressed. A brake pedal (18) remotely controls the braking system (14) and is moveable between a rest position and an applied position. The gear selector mechanism (22) is moveable between a Park position (24) and a plurality of drive positions (26) for remotely controlling the transmission (20). The gear selector mechanism (22) includes an axially movable rod (42) having a bottom end (60) and a detent (62) extending laterally from the rod (42) for disposition in any one of the Park (24) and drive (26) positions. An interlock system (70) initially restrains the detent (62) in the Park position (24) until the brake pedal (18) is moved to the applied position. The interlock system (70) includes an actuator (74) disposed axially under the rod (42) for selectively allowing the detent (62) out of the Park position (24). The actuator (74) is rotatable between an engaged position and a disengaged position. When the brake pedal (18) is moved to the applied position the actuator (74) is rotated to the engaged position such that the bottom end (60) of the rod (42) can be axially depressed into engagement with the actuator (74) allowing the detent (62) to be moved out of the park position (24) and into one of the plurality of drive positions (26).