System Components

System Components
The EPS system is divided into 3 component groups:
^ Upper steering column assembly
^ Steering gear with rack
^ Lower steering spindle

Upper Steering Column Assembly





The upper steering column mechanical section starts at the steering wheel and ends at the connection to the lower steering spindle. The upper steering column is secured by 4 bolts to a bracket which is welded to the instrument panel support frame. In addition, the support frame bracket is secured by 4 bolts to the body.
The electrical section pertains to the EPS servo unit which consists of the EPS . Control Module and the electric motor.
The remaining upper steering column section contains the steering lock with ignition switch and the steering column adjustment mechanism (manual tilt and telescopic).

Servo Unit





The servo unit provides active steering effort assistance as required by steering force and vehicle conditions. The servo unit is located on the upper steering column and is protected in the passenger compartment, it consists of:
^ Electric motor
^ Worm gear
^ Control unit
^ Internal sensors for electric motor speed, steering torque, temperature and voltage.
^ Coilspring cassette for the internal steering torque sensor.
The electric motor and the worm gear in the servo unit produce a new acoustic pattern in the passenger compartment. The system acoustics can be heard in particular situations:
^ When the steering wheel is spun quickly
^ When the steering wheel is turned while the car is stationary
^ When the steering wheel is turned in a quiet atmosphere (e.g. radio not turned on)
This acoustic pattern is not a system fault. The conventional sounds generated by hydraulic steering systems (pump modulation, limiting valve) are eliminated.

Note: The EPS Control Module cannot be replaced separately, the entire assembly with the exception of the Steering Angle Sensor must be replaced as a unit (VIN specific part #).

Lower Steering Spindle





The lower steering spindle connects the upper steering column to the steering gear. It runs in the engine compartment from the bulkhead through two universal joints to the steering gear. The lower steering spindle is encased in a plastic sleeve for corrosion protection. The sleeve is made from high temperature resistant plastic. The two parts of the lower steering spindle interslide in a ball bearing mounting.
The ball bearing mounting is necessary for:
^ Self adjusting length
^ Equalization during steering wheel height adjustment
^ Telescopic collapsing in event of a crash
1. Ball bearing mounting
2. Telescopic compartment

Steering Gear








The steering gear is a purely mechanical rack and pinion system. The steering deflection forces are counteracted by a damped thrust member, which is integrated in the steering gear.
This thrust member has an integral damper element in addition to the tension spring. In the event of rapid steering movements, the rack is not influenced by high deflection forces. Without a damped thrust member, the rack would cause noises when returning at high speed.
1. Steering gear
2. Position lug
3. Thrust member

Note: The thrust member preload is not adjustable.