System Outline

If the brake pedal is depressed suddenly, the ABS controls the hydraulic pressure of the wheel cylinders for all four wheels automatically to prevent the wheels from locking and ensure the directional and steering stability of the vehicle. If the brake pedal is depressed suddenly, the skid control ECU controls the solenoids in the actuators using the signals from the sensors to move the brake fluid to the reservoir in order to release the braking pressure applied to the wheel cylinders. If the skid control ECU detects that the fluid pressure in the wheel cylinders is insufficient, the ECU adjusts the solenoids in the actuators to increase the braking pressure.

The traction control system controls the engine torque, the hydraulic pressure of the driving wheel cylinders, and any slipping of the wheels which may occur at take off or when accelerating the vehicle. This is to optimize the driving power and vehicle stability according to the road conditions.

Unexpected road conditions, vehicle speed, emergency situations, and other external factors may cause an excessive under or over-steer of the vehicle. If this occurs, the VSC system automatically controls the engine power and wheel brakes to reduce the under- or over-steer.

To reduce excessive over-steer :

If the VSC system determines that the over-steer is excessive, it activates the brakes for the outer turning wheels according to the degree of the over-steer, to produce moment toward the outside of the vehicle and reduce the over-steer.

To reduce excessive under-steer :

If the VSC system determines that the under-steer is excessive, it adjusts the engine power and activates the rear wheel brakes to reduce the under-steer.

If an error occurs in the skid control ECU, sensor signals, and/or actuators, the skid control ECU prohibits the brake actuator control and sends an error signal to the engine control module. According to the error signal, the brake actuator will turn off the solenoid and the engine control module rejects any electronically controlled throttle open request from the VSC system. As a result, the vehicle will continue to function, but without the ABS, TRAC, and VSC systems.