GENERAL INFORMATION



Vehicle-speed sensitive electric power steering (whole range type) has been adopted. This system allows a light steering force during stationary steering manoeuvre or low speed driving, and a moderate steering force during medium or high speed driving.
For vehicles with this system, the EPS-ECU controls the motor current according to the vehicle speed and steering force of the steering wheel.
CAN* communication has been adopted in order to communicate with another ECUs for obtaining necessary information related to this control, achieving wiring harness saving and secure data communication.
note *: For more information about CAN (Controller Area Network), refer to GROUP 54C, General Information .

SPECIFICATIONS


Item
Specification
Motor
Type
Permanent magnetic field type
Rated voltage V
DC 12
Rated current Arms
82
Torque sensor
Type
Noncontact type hole IC type
EPS-ECU
Control type
Microcomputer control (32 bit)
Rated voltage V
DC 12

GENERAL DESCRIPTION ON SYSTEM




To improve operational reliability, the dual-circuit system has been adopted for the torque sensor. If any malfunction occurs in the electric power steering system, the fail-safe function of the EPS-ECU is activated, and the output current of the EPS-ECU applied to the motor is turned off. At the same time, the steering system enters manual mode, and informs a driver of the system malfunction by illuminating the warning lamp on the combination meter. The warning lamp illuminates when the following malfunctions occur: open circuit in the electric power steering system wiring harness, poor connection, malfunctions in the EPS-ECU, motor, or sensors.

ELECTRICAL PARTS AND FUNCTIONS


Parts name
Description about function
Sensor
Wheel speed sensor (ABS-ECU or ASC-ECU)
The vehicle speed signal is sent from the ABS-ECU or ASC-ECU to the EPS-ECU via the engine-ECU.
Torque sensor
Detects a steering force, converts it into the voltage signal, and then sends the signal to the EPS-ECU.
Actuator
Motor
Generates assist torque by the steering operation to the column shaft using the signals sent from the EPS-ECU.
Electric power steering warning lamp (in combination meter)
Warns a driver of the system malfunction using the signal sent from the EPS-ECU.
EPS-ECU
Control the actuator (motor) based on the signal sent from sensor.
Controls the self-diagnostic function and fail-safe function.
Controls diagnostic function (Compatible with M.U.T.-III).

SYSTEM CONFIGURATION