Workshop Hints

Workshop Hints
Servo Assistance Reduction or Shutdown
When the EPS system is overloaded, it protects itself by reducing or shutting down servo assistance while retaining a complete mechanical connection for steering. The driver notices the increased steering torque and receives a visual signal from the indicator light.
The following causes will implement protective measures:
^ Servo assistance is reduced/shut down if a fault relevant to EPS is detected in an associated Control Module/sensors (ECM, DSC Control Module, Steering Angle Sensor). A fault code is stored and the indicator light in the instrument cluster illuminates in the event of complete assistance shutdown.
^ Power assisted steering is reduced as EPS internal temperature increases (due to overloading). When reduction of the power is not sufficient to cool the system down, servo assistance is reduced down to zero. A fault is stored and the indicator light in the instrument cluster illuminates. When the temperature cools down, servo assistance returns within 2 seconds to the present requested value.
^ In the event of overvoltage (> 17 V), servo assistance shuts down immediately to protect the output transistors. A fault is stored and the indicator light in the instrument cluster illuminates. When the voltage drops (< 16 V), servo assistance returns within 2 seconds to the present requested value.
^ If an under voltage (< 9 V) is detected, servo assistance is immediately reduced down to
0. A fault is stored and the indicator light illuminates in the event of complete assistance shutdown. When the voltage returns to a level > 10 V, servo assistance increases with in 2 seconds to the requested value. In all cases, the indicator light goes out when the fault is no longer present.

Default Structure
Default 1 Complete shutdown (Control Module, under/over voltage, no assist.
Default 2 When the steering is held in left/right lock position > 40 seconds, power is reduced by 50% (due to increasing internal temperature).
Default 3 Vehicle speed signal is missing, Servotronic feature is deactivated.
Default 4 When the Steering Angle Sensor (LOOS) input is defective, active return centering is deactivated.

Working on Steering Column





Before performing any work on the steering column, it is required that the steering locking pin is engaged in the centering position This prevents turning of the steering spindle during installation.
7. Shipping/service steering locking pin.
- Install before removing column.
- Remove after installing column.
If the steering spindle is fumed, this will break the internal sensors, connecting harness to the EPS -An Control Module.
The connecting harness is located in the coil spring. The spring is installed in the servo unit housing.
When the lower steering spindle is disconnected from the steering gear, it is important when reinstalling to ensure that the center marking on the lower steering spindle is aligned with the center marking on the steering gear. The upper steering spindle and the steering gear are equipped with plastic lugs which determine the correct installation position of the lower steering spindle.

General Information





The mass balance spring (arrow) should be disconnected when work is performed on the upper steering column.

Caution: The mass balance spring is under extreme tension. Be careful not to bend the spring tab mounting retainers.

Note: Only the ignition starter switch, the lock cylinder and the Steering Angle Sensor (LWS) I can be replaced as separate components on the upper steering column.

Diagnosis





System faults and additional information pertaining to vehicle responses are stored in the EPS Control Modules fault memory and can be diagnosed with DlSplus/GT1.