7. Hydraulic unit} · The hydraulic unit essentially consists of

911 Carrera (996) Anti-lock brake system diagnosis 7. Hydraulic unit} The hydraulic unit essentially consists of fast-switchingelectromagnetic valves and a return pump.} Regardless of the pressure in the master brake cylinderI the hydraulic unit can change the fluid pressure to the wheel brake cylinders (holding or reducing pressure). Increasingthe pressure above that of the master brake cylinder is not possible, however. The ABS 5.3 hydraulic unit has three hydraulic outputs (3-channel system) and six electromagneticvalves (three inlet and three outlet valves), The ABS / TC 5.3 hydraulic unit has four hydraulic outputs (4-channel system) and ten electromagnetic valves (four inlet valves / four outlet valves, one switch-overvalve and one intake valve). The intake and switch-overvalves are required so that the return pump can perform two tasks: 1. Return flow to the master brake cylinder (pressure reduction)during ABS control. 2. Supply(pressure increase)to the right or left rear-wheelbrake cylinder during iC control (ABD control). In the case of ASS control at the rear axle, the solenoid valves for both rear wheels are actuated in parallel Gointcontrol as in Solo ABS control (3-channelsystem), 45 -D 13