X-90 (4WD) L4-1591cc 1.6L SOHC MFI (1998)
Hydraulic Control Assembly - Antilock Brakes: Description and Operation
The Antilock Brake System (ABS) actuator assembly is located on the right or left side front wheel housing panel in the engine room and controls the
brake fluid pressure to the front calipers and rear wheel cylinders to prevent wheel(s) lock-up.
It consists of the following two major components whose functions are described below.
-
Hydraulic modulator (included proportioning & differential valve)
-
Motor pack
The hydraulic modulator consists of a solenoid and check-ball which shut off the brake circuit, a piston and ball screws which are driven by the motor
pack.
For structure and operation of P & Differential valve.
The motor pack drives the ball screw included in the hydraulic modulator with three DC motors which can rotate in both directions.
Two motors are used to drive the ball screws for the front brakes respectively and the third one to drive the ball screw for the rear right and left brakes
simultaneously.