Hydraulic Control Assembly - Antilock Brakes: Description and Operation

HYDRAULIC CONTROL UNIT (HCU)
The HCU on the Bosch 5.7 has an integral valve body for controlling the front and rear brakes. Within the HCU are inlet, outlet, and shuttle valves, to release brake pressure as required to avoid wheel lockup, keeping the wheels rolling, and maintain optimum deceleration with stability. The Pump Motor is attached to the HCU which works with the ABS and TCS and is controlled by the CAB. The primary function is to provide extra amount of fluid when needed.