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 (greater than 17 volts), 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 Volts or less), servo assistance returns within 2 seconds to the present requested value.
• If an undervoltage (9 Volts or less) is detected, servo assistance is immediately reduced down to zero. A fault is stored and the indicator light illuminates in the event of complete assistance shutdown. When the voltage returns to a level greater than 10 Volts, 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.