Abstract: The control algorithm for a rear wheel anti-lock brake system includes a subroutine which proportions the applied braking force between front and rear wheel brakes of a vehicle during a braking cycle. The speed of the rear wheels is sensed and used to calculate an estimated vehicle deceleraion. Upon the estimated vehicle deceleration exceeding a deceleration threshold, an isolation valve is closed to hold the brake pressure applied to the vehicle rear brakes constant. Upon further increases of the estimated vehicle deceleration, the isolation valve is selectively opened to increase the rear brake pressure in proportion to the front brake pressure.