Power Steering System Description and Operation (EPS): Notes

The 42-volt rack & pinion electric power steering (EPS) system reduces the amount of effort needed to steer the vehicle using the power steering control module (PSCM) to control the power steering motor to maneuver the steering gear. The PSCM also uses a combination of the torque sensor, motor rotational sensor, 42-volt circuit, battery voltage circuit and serial data circuit to perform the system functions. The PSCM monitors vehicle speed from the engine control module (ECM) via the serial data circuit to determine the amount of steering assist needed to steer the vehicle. At low speeds more assist is provided for easy turning during parking maneuvers. At higher speeds less assist is provided for improved road feel and directional stability.

The EPS system consists of the following components:

• The PSCM
• The power steering motor
• The power steering motor rotational sensor
• The torque sensor
• The steering gear (rack and pinion)
• The accessory power module (APM)

The PSCM and power steering motor are both serviced separately. The power steering motor is serviced separately from the steering gear; however the power steering motor rotational sensor is serviced as part of the steering motor. The torque sensor is integrated with the steering gear pinion and is serviced as part of the steering gear.