The diagonally split master cylinder incorporates the functions of a standard dual master cylinder. However, the primary and secondary master cylinder circuits provide fluid to the brake pressure modulator valve assembly (BPMV) on the Antilock Brake System (ABS), wherein the circuits are divided and individual lines are routed to each wheel brake position. In a diagonally split system, the left rear and the right front brakes are on the primary circuit in the master cylinder, and the right rear and the left front are on the secondary circuit.

While the proportioner valves are often incorporated into a master cylinder, with ABS these valves are located inline with the rear brake pipes, just past the rear of the right wheelhouse.