System Description

This function maintains brake fluid pressure so that the vehicle does not move backwards, even if brake pedal is released to depress accelerator pedal to start the vehicle while it is stopped on an uphill slope by depressing brake pedal.
This function operates when the vehicle is in stop status on a uphill slope of slope ratio 10% or more and selector lever is in the position other than P or N.
Hill start assist function is only for the start aid. It maintains the brake fluid pressure for approx. 2 seconds after releasing the brake pedal, and then decreases the pressure gradually. If the vehicle can start by the accelerator operation, the brake is released automatically and a smooth start can be performed.
Fail-safe function is adopted. When a malfunction occurs in hill start assist function, the control is suspended for VDC function, TCS function, Brake assist function, hill start assist function and Brake force distribution function. The vehicle status becomes the same as models without VDC function, TCS function, Brake assist function, Hill start assist function and Brake force distribution function. However, ABS function and EBD function are operated normally. Refer to Fail-safe .

SYSTEM DIAGRAM

Courtesy of NISSAN

INPUT SIGNAL AND OUTPUT SIGNAL

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

Component	Signal description
Yaw rate/side/decel G sensor	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via communication line *: Yaw rate signal Side G sensor signal Decel G sensor 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 Mainly receives the engine torque request signal from ABS actuator and electric unit (control unit) via CAN communication.
TCM	Mainly transmits the current gear position signal to ABS actuator and electric unit (control unit) via CAN communication.
Combination meter	Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication: Brake fluid level switch signal Parking brake switch signal Mainly receives the VDC warning lamp signal from ABS actuator and electric unit (control unit) via CAN communication.

*: Communication line between yaw rate/side/decel G sensor and ABS actuator and electric unit (control unit)