ABS W/Vehicle Skid Control (VSC)

System Outline

1. ABS Operation
If the brake pedal is depressed suddenly, the ABS controls the hydraulic pressure of the wheel cylinders for all the four wheels to automatically avoid wheel 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 cylinder. If the skid control ECU detects that the fluid pressure in the wheel cylinder is insufficient, the ECU controls the solenoids in the actuators to increase the braking pressure.

2. Traction Control Operation
The traction control system controls the engine torque, the hydraulic pressure of the driving wheel cylinders, slipping of the wheels which may occur at start or acceleration of the vehicle, to ensure an optimal driving power and vehicle stability corresponding to the road conditions.

Traction control SW
The traction control SW is used to stop the TRAC function. After the engine is started, the TRAC system is stopped (turned off) and the TRAC OFF indicator light lights up. When the traction control SW is pressed again, the TRAC system enters the stand by mode. If the engine is stopped and restarted, the TRAC system enters the stand by mode regardless of the traction control SW.

3. VSC Operation
Unexpected road conditions, vehicle speed, emergency situation, and any other external factors may cause large front wheel skid or rear wheel skid of the vehicle. If this occurs, the VSC system automatically controls the engine power and wheel brakes to reduce the front wheel skid or rear wheel skid.

To reduce large rear wheel skid :
If the VSC system determines that the rear wheel skid is large, it activates the brakes for the outer turning wheels depending on the degree of the rear wheel skid to produce the moment toward the outside of the vehicle and reduce the rear wheel skid.

To reduce large front wheel skid :
If the VSC system determines that the front wheel skid is large, it controls the engine power and activates the front and rear wheel brakes to reduce the front wheel skid.

4. Mutual System Control
To efficiently operate the VSC system at its 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 opening of the throttle and reducing the engine output.

Engine control and electronically controlled transmission control
The strong braking force does not interfere with the braking force control of the VSC system by turning off the accel. and reducing changes in the driving torque at shift down.

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 being operated.

5. Fail Safe Function
If an error occurs in the skid control ECU, sensor signals, and/or actuators, the skid control ECU inhibits the brake actuator control and inputs the error signal to the engine control module. According to the error signal, the brake actuator turns off the solenoid and the engine control module rejects any electronically controlled throttle open request from the VSC system. As a result, the vehicle functions regardless of the ABS, TRAC, and VSC systems.