System Outline

If the brake pedal is depressed suddenly, the ABS controls the hydraulic pressure of the wheel cylinders for all four of the 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. Additionally, 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.

The traction control system controls the engine torque, the hydraulic pressure of the driving wheel cylinders, and any wheel slipping which occurs at take off or during acceleration of the vehicle, 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 large a 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 oversteer.

Reducing excessive oversteer :

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

Reducing large understeering :

If the VSC system determines that the understeer is excessive, it controls the engine power and activates the rear wheel brakes to reduce the understeer.

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

Engine fuel injection control

The engine power is prevented from interfering with the VSC brake control by adjusting the fuel injection opening and reducing the engine output.

Engine control and electronically controlled transmission control

Strong engine braking force is prevented from interfering with the braking force control of the VSC system by turning off the accelerator and reducing changes in the driving torque at shiftdown.

VSC system operation indication

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

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 an 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 requests from the VSC system. As a result, the vehicle continues to function but without the ABS, TRAC, and VSC systems.