System Description
SYSTEM DIAGRAM
- Side slip or tail slip may occur while driving on a slippery road or intending urgent evasive driving. VDC function detects side slip status using each sensor when side slip or tail slip is about to occur and improves vehicle stability by brake control and engine output control during driving.
- In addition to ABS function, EBD function and TCS function, target side slip amount is calculated according to steering operation amount from steering angle sensor and brake operation amount from brake pressure sensor. By comparing this information with vehicle side slip amount that is calculated from information from yaw rate/side/decel G sensor and wheel sensor, vehicle driving conditions (conditions of understeer or oversteer) are judged and vehicle stability is improved by brake force control on all wheels and engine output control.
- VDC function can be switched to non-operational status (OFF) by operating VDC OFF switch. In this case, VDC OFF indicator lamp turns ON.
- Control unit portion automatically improves driving stability by performing brake force control as well as engine output control by transmitting drive signal to actuator portion according to difference between target side slip amount and vehicle side slip amount.
- VDC warning lamp blinks while VDC function is in operation and indicates to the driver that the function is in operation.
- CONSULT can be used to diagnose the system diagnosis.
- Fail-safe function is adopted. When a malfunction occurs in VDC function, the control is suspended for VDC function, TCS function, brake assist function and brake force distribution function. The vehicle status becomes the same as models without VDC function, TCS function and brake assist function. However, ABS function and EBD function are operated normally. Refer to Fail-Safe .
INPUT SIGNAL AND OUTPUT SIGNAL
Major signal transmission between each unit via communication lines is shown in the following table:
| Component | Signal description |
|---|---|
| ECM | Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication:
Mainly receives the following signal from ABS actuator and electric unit (control unit) via CAN communication:
|
| TCM | Mainly transmits the following signal to ABS actuator and electric unit (control unit) via CAN communication:
|
| Combination meter | Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication:
Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication:
|
| BCM | Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication:
|
| Chassis control module (with built in steering angle sensor) | Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication:
|
OPERATION CHARACTERISTICS
VDC Function That Prevents Oversteer Tendency
- During cornering, brake force (brake fluid pressure) is applied on front wheel and rear wheel on the outer side of turn. Momentum directing towards the outer side of turn is generated. Oversteer is prevented.
- When changing driving lane on a slippery road when oversteer tendency is judged large, engine output is controlled as well as brake force (brake fluid pressure) of four wheels. Oversteer tendency decreases.
VDC Function That Prevents Understeer Tendency
- During cornering, brake force (brake fluid pressure) is applied on front wheel and rear wheel on the inner side of turn. Momentum directing toward the inner side of turn is generated. Understeer is prevented.
- When applying braking during cornering on a slippery road when understeer tendency is judged large, engine output is controlled as well as brake force (brake fluid pressure) of four wheels. Understeer tendency decreases.