Antilock Brake System

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The Antilock Brake System (ABS) brake system is divided diagonally (two circuits). The vacuum brake servo unit boosts the brakes pneumatically.

Models with ABS do not have a mechanical brake pressure regulator. A specially coordinated software program in the control module determines brake pressure allocation at the rear axle.

ABS malfunctions do not affect the brake system and the booster. Conventional brake system stays operative even without ABS. A change in braking behavior should be checked. When the ABS indicator lamp is on, the rear wheels may lock prematurely during braking!

Fig 1: Identifying Hydraulic Unit And Control Module And Brake Booster

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

1 - Hydraulic unit and control module

2 - Brake booster

The control module and hydraulic unit form one component. Separation is not possible. The hydraulic pump must also not be separated from the hydraulic unit.