The CAS control unit checks the status information sent from the electric steering lock. If the status information shows a fault, the CAS control unit refuses start authorization and therefore provides no release for terminal 15.
The CAS control unit is the interface with the START-STOP button and ring aerial. The ring aerial on the steering column transmits the key data. The ring aerial is used for communication between the transponder chip (in the ID transmitter) and the CAS control unit. In unfavorable situations (e.g., ID transmitter fault, malfunction of radio transmission to the ID transmitter), the ID transmitter may not be found via the passenger compartment’s interior aerials.
Communication via the ring aerial makes it possible for the CAS control unit to identify a valid ID transmitter and start enabling.
Depending on the vehicle equipment fitted, the comfort access system’s control unit function is integrated into the CAS control unit. Outside door handle electronics are incorporated in each one of the outer door handles. Changes in door handle status are recorded by the external door sensors’ sensors and transmitted to the CAS control unit. The ID transmitter is requested via an aerial signal from the CAS control unit to identify itself. The CAS control unit emits the aerial signal via the exterior aerials.