Theory Of Operation

The Electronic Power Steering (EPS) system employs a column mounted electric power steering unit along with a manual steering rack and pinion to provide a variable power assisted steering with reduced parasitic engine load. The EPS controller monitors two steering wheel position sensors to determine the absolute position of the steering shaft and determines driver input via a steering wheel torque sensor. In addition, the EPS controller uses four hall-effect position sensors to monitor the absolute and commanded position of the motor. The EPS controller obtains vehicle speed, alternator output, and steering mode information, and broadcasts warning lamp status and service diagnostic information, on CAN C. During normal driving, as the driver turns the wheel, the torque sensor value changes based on the effort the driver uses to turn the wheel. The controller uses this information, along with the steering wheel absolute position and vehicle speed, to determine the amount torque required from the motor. Voltage is then provided to the motor to provide power steering assist.