A control valve for use in a dual or split brake system having a switch-operating piston movable from a centered position toward opposed translated positions in response to a predetermined differential between separately supplied fluid pressures acting thereon and a metering piston normally movable to effect a metered application through said control valve of one of the supplied fluid pressures. A bypass passage is provided through the metering piston for connecting the one supplied fluid pressure and the applied fluid pressure in open pressure fluid communication to obviate the metering function of the metering piston, and the switch-operating piston is provided with a portion slidable in one end of the bypass passage to normally interrupt pressure fluid communication therethrough between the one supplied fluid pressure and the applied fluid pressure when said switch-operating piston is in its centered position.