Grand Marquis V8-281 4.6L SOHC (1992)
Hydraulic Control Assembly - Antilock Brakes: Description and Operation
The hydraulic control unit (HCU) is located on the front lefthand side of the engine compartment. It consists of a valve body assembly, pump, motor
assembly and brake fluid reservoir with fluid lever indicator assembly. During normal braking, fluid from master cylinder enters the HCU through two
inlet ports at the rear of the HCU. The fluid passes through four normally open inlet valves, one to each wheel. When electronic control unit (ECU)
senses wheel lock conditions, the ECU produces a pulse to appropriate inlet valve which closes that valve. This prevents any more fluid from entering
affected brake. The ECU senses the wheel again, if the wheel is still decelerating the ECU then pulses open the normally closed valve which decreases
pressure trapped in line.
