Hydraulic Control Assembly - Antilock Brakes: Description and Operation

Hydraulic control unit (HCU)
The HCU consists of a motor pump assembly in which motor sensor is built, and valve block for controlling ABS pressure.
Reference
Diameter of front brake pipe hole-pitch: FL, RL: 0.47 inch (12 mm)
Diameter of rear brake pipe hole-pitch: FR, RR: 0.39 inch (10 mm)

The motor pump is a reciprocal 2-line pump and transmits enough pressure to the wheel system, and the valve block controls fluid pressure to each wheel cylinder.
ABS module
The ABS module illuminates the ABS warning lamp when an ABS failure occurs.

ABS control unit
The ABS control unit performs the following functions.
^ Controls the ABS
^ Calculates vehicle speed
^ Self-diagnostics: Stores malfunction codes, performs ABS control unit self-diagnostic and fail-safe functions with two separated microprocessors.
The ABS control unit continuously checks locking of each wheel and controls each valve to adjust brake fluid pressure if required. The ABS control unit also checks that components are working properly and stops ABS if a malfunction is detected.
Then, it is operated as a standard brake system.