VDM control unit outputs
All outputs are compatible with diagnostics and protected against short-circuit. The outputs include controls for:
- Pressure regulating valves for front and rear axle
- Failsafe valve
- Directional valve
- Intake restrictor valve
- 5 V power supply for the sensors:
- Pressure sensors at the front and rear axle
- Switch-position detector (SSE)
The valves are controlled by the supply of current regulated by pulse-width modulation (PWM). The current measurements of the individual coil currents are designed with redundancy. The valve currents are mutually checked for plausibility on a continuous basis.
Thanks to the current measurement, the pressure can be set more precisely and the switch valves can be monitored electronically. Fault symptoms of the output signals are:
- Short circuit to Terminal 30 and Terminal 31
- Open circuit and
- Valve short circuits
- Sensor power supply faults
A message is sent to the DME via the FlexRay bus from the central dynamic handling controller on the ICM. The message contains information on how much power the tandem pump currently requires to supply the active anti-roll bars. In this way, output at the engine can be increased to satisfy the additional power requirement. A regular data signal (alive signal) is broadcast and read by other VDM control units to identify whether the system is still active. In addition, a function status signal is broadcast which communicates the status of the ARS function. The VDM control unit transmits an additional status message via the FlexRay to the instrument cluster in order to actively initiate display messages.
That status message is assigned a priority among all suspension/steering messages by the message co-ordinator on the ICM control unit and passed to the instrument cluster. All signal faults are recorded and permanently stored in the fault memory. If the alive signal fails, the ICM control unit automatically sends a message to the instrument cluster to activate the ARS warning lamp.