Steering System

Steering System

Electronic Power Assist Steering (EPAS) System

NOTICE: The steering sensor contains a clockspring that will be damaged if the steering column is not handled correctly. To prevent damage to the steering sensor, use the service bolt (HB1) to lock the steering column in the straight ahead position before disconnecting the steering column from the steering gear. Damage caused to the steering sensor by failing to lock the steering when disconnecting the column from the steering gear leads to a complete failure of the Electronic Power Assist Steering (EPAS) system and requires a new EPAS column to be installed.

The Electronic Power Assist Steering (EPAS) system consists of the following components:

- Power Steering Control Module (PSCM) - the PSCM controls the functions of the EPAS system and communicates with other modules on the High Speed Controller Area Network (HS-CAN). The PSCM is attached to the EPAS column assembly and cannot be serviced separately.
- Motor - the EPAS column uses a 12-volt brushless, reversible motor, a worm gear and a reduction gear to control the steering effort. The motor is attached to the EPAS column assembly and cannot be serviced separately.
- Steering sensor - the PSCM uses the steering sensor to determine force applied to, speed and direction of the steering wheel. This information is transmitted to other modules along the HS-CAN. The sensor is attached to the EPAS column assembly and cannot be serviced separately.
- Steering column shaft - the steering column shaft connects the EPAS column assembly to the steering gear and can be serviced separately. For additional information, refer to Steering Column Service and Repair.
- Steering gear - the steering gear is a rack and pinion type gear, which is serviced as an assembly and contained within a one-piece aluminum housing. The steering gear uses tie-rod ends to connect the gear to the wheel knuckles. The steering gear can be serviced separately from the EPAS column assembly. For additional information, refer to Power Steering Service and Repair.
- Tie-rod ends - one inner and outer tie rod is located at each end of the steering gear and can be serviced separately. For additional information, refer to Power Steering Service and Repair.

The EPAS system provides power steering assist to the driver by replacing the conventional hydraulic valve system with an electric motor coupled to the steering shaft. The motor is controlled by the PSCM which senses the steering effort using sensors mounted between the steering column shaft and the steering gear. Steering assist is provided in proportion to the steering input effort and vehicle speed.