Fluid loss due to external leakage
The hydraulic circuits of the ARS system and the steering system are linked to one another by virtue of a shared fluid reservoir. The VDM control unit monitors the fluid level in the reservoir by means of a fluid level sensor. Loss of fluid due to external leakage in the hydraulic circuits of the ARS or steering systems leads to a drop in the fluid level in the shared fluid reservoir. Fluid loss can result in total failure of the ARS system and impairment of the steering system. If the fluid level sensor trips, the ARS system is set to failsafe mode and a fault is registered on the VDM control unit.
Scheme 19
Simultaneously, a CC message is issued warning of impairment of ARS system and steering system function. The driver is instructed to carefully bring the vehicle to a halt and switch off the engine.
Initialization/reset performance
When the VDM control unit is booted up, various checks and initialization routines are executed. They include checks of the electrical circuits for the valves and the sensors within the system, an authentication check involving querying the VIN number on the CAS and testing FlexRay communication. The system is not enabled until the tests have been successfully completed. Occurring faults are stored and displayed.
Initialization/reset behavior
Different checks and initialization are carried out when the EHC control unit is powered up after a reset (triggered by an undervoltage or also by load cutout off VA_AUS).
The system is only enabled after the tests have been successfully completed and starts to execute the control programs on a cyclical basis. Occurring faults are stored and displayed.