Antilock Brakes / Traction Control Systems: Description and Operation

Brake System Construction





The Antilock Brake System (ABS) controls the fluid pressure applied to the wheel cylinder of each brake from the master cylinder so that each wheel is not locked even when hard braking is applied. This ABS is a 4-wheel type which controls the fluid pressure applied to the wheel cylinder of each of the four brakes to prevent each wheel from getting locked.
The component parts of this ABS includes the following parts in addition to those of the conventional brake system.
^ Wheel speed sensor which senses revolution speed of each wheel and outputs its signal.
^ In this ABS, ABS hydraulic unit (actuator assembly), ABS control module, pump motor relay and fail-safe relay are combined as one component.
^ ABS control module (3) which sends operation signal to ABS hydraulic unit (13) to control fluid pressure applied to each wheel cylinder based on signal from each wheel speed sensor so as to prevent wheel from locking.
^ ABS hydraulic unit which operates according to signal from ABS control module to control fluid pressure applied to wheel cylinder of each of 4 wheels,
^ Fail-safe (solenoid valve) relay (10) which supplies power to solenoid valve in ABS hydraulic unit and ABS pump motor relay (9).
^ Pump motor relay which supplies power to pump motor in ABS hydraulic unit.
^ "ABS" warning lamp (8) which lights to inform abnormality when system fails to operate properly.
^ G sensor which detects body deceleration speed (4WD vehicle only).