Description And Operation: Operation

FUNCTIONAL DESCRIPTION

The EPS module is a power assisted steering device designed to reduce the effort required for steering the vehicle by using the torque from a torque angle sensor located on the steering gear pinion.
The EPS manages and controls the system by processing the input information and using a pre-programmed operating logic. The EPS module determines the direction of rotation and the supply current for the electric motor, producing the desired servo-assistance effect.
An "Electric Power Steering Failure" warning indicator lamp is present on the Instrument Panel Cluster (IPC) to notify the vehicle operator of any potential EPS concerns.

NOTE:

If battery power is lost the EPS module loses the sensor reference value coming from the pinion. On re-connection of battery power it will be necessary to manually re-initialize the sensor.

FUNCTIONAL OPERATION

During Ignition ON:

In the memory of the EPS module, there are stored the values of the rotor Revolution Per Minute (RPM) sensor, reference sensor and the calculated steering angle value.
The checks on plausibility among the synchronization of the calculated steering angle, the reference sensor and the wheel speed are continuously performed.
Whenever the deviation between the calculated steering angle and the reference sensor value is greater than 2 degrees the EPS module performs a new initialization.

During Ignition OFF:

Cyclically the part of the EPS module dedicated to the control of the rotor RPM sensor is activated to check the integrity of the system. If the rotor RPM sensor senses a rotation, the part of the EPS module dedicated to the control awakes to receive and store the new values sent from the sensor.
As soon as the rotor speed sensor ceases to communicate movements of the rotor, the system will return to making cyclical control.
During ignition off the EPS module does not send a signal of steering angle and does not provide power assistance.
Power to the EPS module is supplied from the battery by a fuse protected circuit in the front Power Distribution Center (PDC).
The Body Control Module (BCM) supplies the ignition feed to the EPS module.
The EPS module is on the Controller Area Network - Chassis (CAN-C) data bus system and communicates directly to the BCM. The BCM is responsible for sending the signal to the IPC to illuminate the warning indicator lamp in order to alert the vehicle operator of a potential EPS concern.