For 1990-2009 cars

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 pressure modulator valve assembly on the antilock brake system (ABS), wherein the circuits are divided and the individual lines are routed to each wheel brake position. In a diagonally split system, the right rear and left front brakes are on the primary circuit in the master cylinder, and the left rear and right front are on the secondary circuit.

While proportioner valves are often incorporated into a master cylinder, with ABS these valves are located in series with the rear brake pipes, just forward of the left rear wheelhouse.