System Description

Side slip or tail slip may occur while driving on a slippery road or intending an 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 TCS function, ABS function and EBD function, target side slip amount is calculated according to steering operation amount from steering angle sensor and brake operation amount from pressure sensor. By comparing this information with vehicle side slip amount that is calculated from information from yaw rate/side 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 4 wheels and engine output control.

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VDC function can be switched to non-operational status (OFF). 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, brake force distribution function, and hill start assist function. The vehicle status becomes the same as models without VDC function, TCS function, brake assist function, brake force distribution function, and hill start assist function. However, ABS function and EBD function are operated normally. Refer to Fail-Safe .
NOTE: VDC has the characteristic as described here, This is not the device that helps reckless driving.

SYSTEM DIAGRAM

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INPUT SIGNAL AND OUTPUT SIGNAL

Major signal transmission between each unit via communication lines is shown in the following table:

Component	Signal description
BCM	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Stop lamp switch signal Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication: Stop lamp request signal
ECM	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Accelerator pedal position signal Engine speed signal Engine torque signal
TCM	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Current gear position signal AT accept permission signal Shift position signal
Chassis control module	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Active trace control signal
IPDM E/R	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Ignition switch ON signal
Steering angle sensor	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Steering angle sensor signal
Combination meter	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Brake fluid level switch signal Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication: ABS warning lamp signal Brake warning lamp signal VDC OFF indicator lamp signal VDC warning lamp signal

OPERATION CHARACTERISTICS

VDC Function That Prevents Oversteer Tendency

During a cornering, brake force (brake fluid pressure) is applied on front wheel and rear wheel on the outer side of turn. Moment directing towards the outer side of turn is generated. Oversteer is prevented.

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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 4 wheels. Oversteer tendency decreases.

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VDC Function That Prevents Tendency

During a cornering, brake force (brake fluid pressure) is applied on front wheel and rear wheel on the inner side of turn. Moment directing towards the inner side of turn is generated. Understeer is prevented.

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Applying braking during a 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.

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