Functions Of Sensors And Actuators

Name		Function
ABS control module and hydraulic control unit (ABSCM&H/U)	ABSCM section	It determines the conditions of the wheels and the vehicle body from the wheel speed data and controls the hydraulic unit depending on the result. When the ABS is active, the ABSCM provides the automatic transmission control module with control signals which are used by the module for cooperative control of the vehicle with the ABSCM. Whenever the ignition switch is placed at ON, the module performs a self diagnosis sequence. If anything wrong is detected, the module cuts off the system. It communicates with the SUBARU select monitor.
	H/U section	When the ABS is active, the H/U changes fluid passages to the wheel cylinders in response to commands from the ABSCM. It constitutes the brake fluid passage from the master cylinder to the wheel cylinders together with the piping.
	Valve relay section	It serves as a power switch for the solenoid valves. It operates in response to a command from the ABSCM.
	Motor relay section	It serves as a power switch for the pump motor. It operates in response to a command from the ABSCM.
ABS wheel speed sensor		Detects speed of each wheel and sends to the ABSCM.
Magnetic encoder		Incorporated with the hub unit bearing and causes the ABS wheel speed sensor to generate electrical signals.
G sensor		It detects a change in acceleration in the longitudinal direction of the vehicle and outputs it to the ABSCM as a voltage signal.
Stop light signal		Detects ON-OFF status of the brake pedal and sends to the ABSCM. The ABSCM uses it to determine ABS operation.
ABS warning light		It alerts the driver to an ABS fault.
Automatic transmission control module		It provides gear controls and changing power transmission to front and rear wheels in response to control signals from the ABSCM.
Brake warning light		It alerts the driver to an EBD fault. This warning light is also used for parking brake warning and brake fluid level warning.

MEMO

Fig 1: Anti-Lock Brake System - Circuit Diagram

Courtesy of SUBARU OF AMERICA, INC.