System Description

SYSTEM DIAGRAM

Parts name	Function
Power steering control module	Refer to STEERING GEAR ASSEMBLYSteering Gear Assembly.
EPS motor	Refer to STEERING GEAR ASSEMBLYSteering Gear Assembly.
Power steering torque sensor	Refer to STEERING GEAR ASSEMBLYSteering Gear Assembly.
ECM	Transmits mainly the following signals to power steering control module via CAN communication. Engine status signal Receives mainly the following signals from power steering control module via CAN communication. Battery supply current signal EPS torque on signal
ABS actuator and electric unit (control unit)	Transmits mainly the following signals to power steering control module via CAN communication. Vehicle speed signal (ABS)
Steering angle sensor	Transmits mainly the following signals to power steering control module via CAN communication. Steering angle sensor signal
Combination meter	Turns ON the power steering warning light according to the signal from the power steering control module via CAN communication.

DESCRIPTION

EPS system consists mainly of power steering control module, EPS motor, power steering torque sensor.
EPS system calculates a control signal to transmit to the EPS motor based on information received from ECM, ABS actuator and electric unit (control unit) and steering angle sensor via CAN communication and information received from power steering torque sensor.
Power steering control module performs an arithmetical operation on data, such as steering wheel turning force (sensor signal) from the power steering torque sensor, vehicle speed signal, etc. Then it generates an optimum assist torque signal to the EPS motor according to the driving condition.
After engine start, the EPS system performs control.
When a malfunction occurs in the system, the fail-safe function stops the EPS system (manual steering state) or restricts its operation (Constant steering assist level state). Refer to Fail-Safe.
Power steering control module decreases the output signal to EPS motor while extremely using the power steering function (e.g., full steering) consecutively for protecting EPS motor and power steering control module (Overload protection control). Refer to Protection Function.

CONDITIONS FOR POWER STEERING WARNING LIGHT ON

Turn ON when there is a malfunction in EPS system. If indicates that fail-safe mode is engaged and enters a manual steering state (Control turning force steering wheel becomes heavy).
Also turns ON when ignition switch is ON, for purpose of light check. Turns OFF after the engine starts, if system is normal.

Condition	Power steering warning light
Ignition switch ON. (Light check)	ON
After engine start (steering assist force is generated)	OFF
When steering assist is stopped	ON