Hydraulic Unit: Notes
The hydraulic unit consists of 3 electric solenoid valves and a return delivery pump. Each of the electric solenoid valves are for left and right front electric solenoid valves and the mutually regulated rear solenoid valves.
The hydraulic unit can change hydraulic pressure to each of the brakes, independently of the pressure in the brake master cylinder. However, a higher brake master cylinder pressure is not possible.
Depending on amperage, the hydraulic pressure in each wheel cylinder can be as follows: increased (pressure building up phase), maintained (pressure holding phase) or reduced (pressure dropping phase).
The hydraulic unit on the 928S is located on a bracket in an opening on the inner left front wheelwell. Brake line connections are accessible from the engine compartment. On the 944 series, the hydraulic unit in the back of the right front wheelhouse. It is mounted on a bracket with a protective cover.