A control system for a vehicle (10) having an air braking system includes a supply line (13) for receiving a supply of compressed air for the air braking system. One or more brake members (19) are provided in fluid communication with the supply line (13) and controllable such that upon receipt of compressed air, the brake members (19) become disengaged to facilitate movement of the vehicle (10). Upon removal of the compressed air, the brake members (19) become engaged to prevent movement of the vehicle (10). An isolator device (20) is positionable within the supply line (13) upstream of the brake members (19) and is controllable to operate in a first state wherein the compressed air flows along a supply line (16) and a second state wherein the compressed air is prevented from flowing along the supply line (16) to the brake members (19).