The Power of CAS4: Understanding BMW's Car Access SystemCAS, short for Car Access System, is the master control unit responsible for controlling access into your BMW (central locking system) and access to various vehicle functions. The CAS4 generation offers enhanced features and improved functionality.
Versions of CAS: CAS comfort access system (CA: Comfort Access)CAS with comfort access system CAS without comfort access system but including electric steering lock (ELV)
CAS with comfort access system and including electric steering lock (ELV)
 
Functions of CAS4: 
CAS4 integrates various functions, providing a wide range of signals to other bus users in the vehicle electrical system. Some of these functions include:Terminal control, Comfort start, Remote control of central-locking system, Centralized control of central locking and power windows, Centralized control for CA (Comfort Access), Wake-up of MOST via K-CAN2 for telematics service, Central data source for vehicle order and redundant data storage for vehicle data, Central control of electric steering lock (if fitted)
 
CAS4 Control Unit:The CAS4 control unit is the master controller for various systems, including terminal control, power windows, central locking system, comfort access, and more. It evaluates signals from the brake light switch and clutch switch to initiate engine start release upon pressing the start/stop button.
Electric Steering Lock:The electric steering lock (ELV) is connected to the CAS4 control unit via the body bus. The ELV is supplied with voltage and activated by the CAS4 control unit, ensuring the vehicle remains secure when parked.
Comfort Access System: CAS4 supports Comfort Access, which allows you to unlock your BMW without using a physical key. The exterior door handle electronics are integrated into each outer door handle, transmitting status changes back to the CAS4 control unit. The ID transmitter is requested via an aerial signal from the CAS4 control unit to identify itself.
Aerial Signals: Various aerials are required for communication with the ID transmitter: interior and exterior aerials for Comfort Access, and an aerial for remote control service. All these signals connect to the CAS4 control unit, which processes data and executes corresponding functions. Engine Compartment Lid Contact Switch: The CAS4 control unit evaluates the status of the engine compartment lid contact switch for automatic start/stop function (MSA) and anti-theft alarm system (DWA). In summary, the CAS4 is a vital component in your BMW, controlling access, security, and various vehicle functions. Its advanced features ensure a seamless driving experience while keeping your car secure. If your original unit is beyond repairs, we can provide you with a "donated" used one + cloning of original data (when available)