Abstract: An anti-lock brake system having a switchable orifice control valve disposed between the master brake cylinder and the brake assembly. The switchable orifice control valve, having a valve body, a stationary member, a movable member and a solenoid coil actuated armature. The switchable orifice control valve has a normally open state, a closed state and a third state during an anti-lock mode of operation. In the third state the brake fluid from the master brake cylinder to the brake assembly flows through a calibrated re-apply orifice which controls the rate at which the pressure of the fluid being applied to the brake assembly is increased at a predetermined rate. The switchable orifice control valve is held in the third state by a pressure differential orifice between the input and output ports of the switchable orifice control valve.

Abstract: Method and system are provided for "filtering out" a faulty wheel speed input signal in a vehicle control system, such as an ABS and/or TC system in order to ensure that the faulty wheel speed input signal does not contaminate or corrupt wheel speed information contained in the other wheel speed input signals. If such faulty wheel speed input signal indicates an abnormally high speed, it will increase the other wheel speed information if undetected. The wheel speed information is essential in detecting wheel instability or slip. It is important that wheel speed is not over-estimated since this may result in false slip detection and false ABS activation. Over-estimation of the vehicle speed would occur if the information from a spinning wheel is not properly filtered or compensated for. In one embodiment of the present invention, a bad sensor is detected by detecting and compensating for a single outlying ramp (outlier) of wheel speed.