EPS SYSTEM : System Description: Notes

EPS control unit performs an arithmetical operation on data, such as steering wheel turning force (sensor signal) from the torque sensor, vehicle speed signal, etc. Then it generates an optimum assist torque signal to the EPS motor according to the driving condition.
In case of an error in the electrical system, the fail-safe function stops output signals to the EPS motor. Refer to "EPS SYSTEM : FAIL-SAFE ".
EPS control unit decreases the output signal to EPS motor while extremely using the power steering function (e.g., full steering) consecutively for protecting EPS motor and EPS control unit (Overload protection control). Refer to "EPS SYSTEM : PROTECTION FUNCTION ".
EPS control unit will decrease assistance under the following 2 conditions.
- Extensive steering at low speed will cause the EPS control unit and EPS motor to heat up, once temperature reaches critical point EPS control unit will reduce current to reduce heat up. System will recover as temperature lowers (reduced or no assistance).
- Holding steering on rack-end (full lock) for 1 second will cause the system to engage rack-end protection. This reduces assistance down to 50% in order to prevent heat up. Assistance is immediately returned to 100% when steering released or turned away from rack-end.
Fig 1: EPS System Description Chart
Courtesy of NISSAN MOTOR CO., U.S.A.
In SPORT mode, changes the steering assist characteristic to enhance a stable steering feel according to the mode signals from multi display unit via CAN communication. (Models with Integrated Control System)