System Description

With Electric Parking Brake System and Automatic Brake Hold Function

Side slip or tail slip may occur while driving on a slippery road or attempting an urgent evasive driving maneuver. 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 under steer or over steer) 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) 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, brake force distribution function, hill start assist function. The vehicle status becomes the same as models without VDC function, TCS function, brake assist function, brake force distribution 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 parts	Signal description
Combination meter	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication. Parking brake switch signal 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 VDC OFF indicator lamp signal VDC warning lamp signal Brake warning lamp 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 status signal ECM malfunction signal
IPDM E/R	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication. Ignition switch ON signal
TCM	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication. Current gear position switch signal
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. Steering angle sensor signal Steering angle sensor malfunction signal

OPERATION CHARACTERISTICS

VDC Function That Prevents Over steer Tendency

During a 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. Over steer is prevented.

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Changing driving lane on a slippery road, when over steer tendency is judged large, engine output is controlled as well as brake force (brake fluid pressure) of four wheels. Over steer 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. Momentum directing towards the inner side of turn is generated. Under steer is prevented.

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Applying braking during a cornering on a slippery road, when under steer tendency is judged large, engine output is controlled as well as brake force (brake fluid pressure) of four wheels. Under steer tendency decreases.

Courtesy of NISSAN NORTH AMERICA, INC.