Car Access System (CAS)

The following functions are grouped in the Car Access System (CAS):

• Terminal control
  
• Comfort start with electronic car immobilisation system
  
• Remote control
  
• Central control of the central locking system
  
• Central control of the power windows
  
• Gateway module for K-CAN
  

Terminal control

Terminal R and 15 as well as the cable for activation of the data bus PT-CAN (wake-up line, terminal 15 WUP) are controlled in the CAS.

• When the remote control is inserted in the ignition lock, the CAS transmits the information ”terminal R On” via the data buses K-CAN SYSTEM and K-CAN PERIPHERIE. Control units that are active as of terminal R (e.g. wiper module) are thus activated. There is no separate cable for terminal R.
  
• When the remote control is inserted in the ignition lock and then the start-stop button is pressed, terminal 15 is switched on. The CAS forwards this information across the data buses to the control units. In addition, CAS has four terminal 15 outputs to which control units or release relays are connected.
  
• When terminal 15 is switched on, the control units on the data bus PT-CAN are activates (woken up) across the cable terminal 15 WUP.
  

Comfort start with electronic car immobilisation system

The comfort start enables operator-friendly start of the engine, as the starter motor remains on until the engine is running.

The electronic vehicle immobilisation unit ensures that an engine start-up is only possible when a remote control belonging to the car or the spare key is inserted in the ignition lock.

Function of remote control

The remote control enables operation of the central locking system as well as various special functions by means of a radio transmitter. The CAS receives the radio commands across the rear-window aerial and transmits corresponding commands across the data buses for execution of the desired function.

The radio transmission of the remote control commands is encrypted via a random code, thus excluding any manipulation. The CAS manages the random codes of up to 4 radio transmitters (remote controls)

When the vehicle is unlocked, the personalisation number stored in the radio transmitter (remote control) is also transmitted to the CAS. This number controls the vehicle settings coded via Key Memory. The CAS forwards the personalisation number across the data buses to the control units. The settings dependent on the Key Memory are stored in each control unit.

Central control of the central locking system

The CAS controls the functions of the central locking system. After reception of an operation request (e.g. via remote control, lock contact or center lock button), the CAS decides whether the central locking system is to be unlocked, locked or secured, and transmits the corresponding command via the K-CAN data buses (K-CAN SYSTEM and K-CAN PERIPHERIE) to the control units.

Central control of the power windows

The CAS controls the convenience functions, the child safety lock and the power window activation/deactivation depending on the different national versions (encoding data).

Gateway module for K-CAN

Two K-CAN data buses are fitted in the vehicle: the K-CAN SYSTEM and the K-CAN PERIPHERIE. The reasons for this are:

• Availability of important vehicle functions also in the case of a wire short circuit, as the systems of the K-CAN PERIPHERIE are fitted in the crash area of the vehicle.
  
• Reduction of the bus load
  

The CAS connects the two data buses and enables exchange of information between the two K-CAN buses.