System Outline

If the brake pedal is depressed suddenly, the ABS controls the hydraulic pressure of all four wheel cylinders automatically to prevent the wheels from locking and to ensure the directional and steering stability of the vehicle. If the brake pedal is depressed suddenly, the skid control ECU with actuator 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 with actuator detects that the fluid pressure in the wheel cylinder is insufficient, then the ECU with actuator 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 wheel slippage which may occur at take off or when accelerating the vehicle, to ensure optimal driving power and vehicle stability regardless of the road conditions.

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

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 depending on 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.

To efficiently operate the VSC system at the optimal level, the VSC system and other control systems are mutually controlled while the VSC system is being operated.

Engine throttle control

The engine power does not interfere with the VSC brake control by controlling the throttle opening and reducing the engine output.

Engine control and electronically controlled transmission control

The accelerator is turned off and torque changes caused by down-shifting are reduced to prevent a strong braking force from interfering with the braking force control of the VSC system.

VSC system operation indication

The slip indicator light flashes and the buzzer sounds intermittently to warn the driver that the current road is slippery, while the VSC system is operating.

If an error occurs in the skid control ECU with actuator, sensor signals, and/or actuators, the skid control ECU with actuator inhibits the brake actuator control and inputs an error signal to the engine control module. In response 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 remains functional, but without the ABS, TRAC, and VSC systems.