Car Access System

Car Access System
The Car Access System (CAS) control module regulates access and the access options to the vehicle. The CAS control module is the master control module, e.g. for the following systems.
- Terminal control
- Electronic vehicle immobilization
- Comfort Access (if equipment is present)
- Electrical steering interlock (if equipment is present)
- Central locking
- Power windows

Brief description of components
The following components for the Car Access System are described:

CAS: Control module
The Car Access System (CAS) is the control module that controls access to the vehicle (Comfort Access) and its functions (key identification, electronic immobilizer, enable for engine start).

The CAS control module is the master control module for the power windows and central locking system functions. This means it checks the enable conditions before the junction box electronics control module is permitted to activate the central locking system and the footwell module and junction box electronics control modules are permitted to activate the power windows.

The CAS control module is the master controller for the terminal control, i.e. it activates terminal 15, terminal 30B and terminal 50.

The electronic steering lock is activated by the CAS control module.

The CAS control module evaluates the signals of the brake-light switch and of the clutch module.

The CAS control module is connected directly to the K-CAN2 (Body CAN2).

START-STOP button
Together with the remote control, the START-STOP button is used to start the vehicle. The remote control contains an authorization code for the relevant vehicle.

Two Hall sensors are installed in the START-STOP button. The Hall sensors detect whether the START-STOP button is operated. If the CAS detects an authorized remote control, terminal R is switched on.

Pressing the START-STOP button initializes the engine start. Here, the CAS control module checks the following requirements:
- With automatic transmission, selector-lever position "P" or "N" and brake operation
- With manual transmission, clutch operation

When all the requirements have been met, the engine is started by the CAS control module in that terminal 50 to the starter motor is activated. To stop the engine, press the START-STOP button once again. The engine is switched off; terminal R remains switched on. On vehicles with automatic transmissions, the engine can only be stopped with the vehicle at a standstill when the parking lock is engaged.

The START-STOP unit is connected via a 14-pin plug-in connection to the CAS control module.

NOTE: Emergency function while the vehicle is being driven.

For safety reasons, the engine can be stopped while the vehicle is being driven by pressing the START-STOP button. A renewed start in this case is possible without additional brake operation or clutch operation.

Electric steering lock
The electric steering interlock (ELV) is an anti-theft device for vehicles with manual transmissions.

The ELV is a control module without a connection on the CAN bus. The ELV is supplied and activated by the CAS control module. The CAS control module is the master control module for the ELV. Faults in the ELV are stored in the CAS control module.

After successful authentication of a valid key by the CAS control module, the ELV is supplied with current to unlock it and terminal 15 is switched. Once the ELV has been unlocked and secured, the engine can be started by actuating the START-STOP button.

The CAS control module checks the status information sent by the ELV. If the message after unlocking is not fault-free information with the ELV status "ELV unlocked and secured", the CAS control module is not allowed to grant starting approval and does not enable terminal 15.

The electrical steering interlock can only be locked when the vehicle is at a standstill and the engine has stopped. After the door is opened or the central locking system is secured, the ELV is locked.

If no unlocking procedure or locking procedure is carried out, the electrical steering interlock is secured and without current.

The electrical steering interlock is connected to the CAS control module via the K bus.

Remote control key and identification sensor
The following functions (depending on the vehicle equipment) are triggered by the rechargeable remote control key or battery-operated identification sensor with 3 or 4 buttons respectively.
- Opening and closing the central locking system
- Arming and disarming the anti-theft alarm system
- Deactivate interior sensor and inclination sensor
- Triggering the panic mode (if encoded)
- Unlocking the trunk lid
- Opening and closing the luggage compartment lid
- Switching on the interior lighting
- Convenience opening and closing of the power windows and sliding roof (if encoded)

Electronic outer door handle module
The outside door handle electronics are located in the outer door handle of each door.

The 3 sensors in the outside door handle electronics send the following signals to the CAS control module:
- Unlock: When a hand reaches into the handle recess via capacitive sensor 1
- Unlock: When a hand pulls on the outside door handle via tension sensor (redundant to capacitive sensor 1)
- Locking and deadlocking: On contact with the sensitive area of the door handle via capacitive sensor 2

A built-in antenna also sends radio signals in order to check for an ID transmitter located on the outside of the driver's door or passenger's door.

Comfort Access antennas
Various antennas are required for communication with the identification sensor: Interior and exterior antennas The antennas transmit on a frequency of 125 kHz. The wave emitted by the antennas are spherical in form. The identification sensors are asked to identify themselves via the antennas. All the radio signals are encrypted and thus protected against unauthorized access.

FBD receiver
The task of the FBD receiver is to pick up the radio signals, process these signals as well as to forward data to the CAS control module. Further data processing as well as the corresponding function execution take place in the CAS control module.

Notes for Service department

General information

Redundant data storage:
If the instrument cluster is replaced, the stored data (e.g. total distance reading) must be retained. This will make it possible to detect any evidence of manipulation. In order to guard against manipulation, the following data are stored redundantly (second copy) in the Car Access System (CAS):
- Vehicle identification number
- Total distance (kilometer reading)
- Data for the service scopes of Condition Based Service (CBS)

The data is verified each time terminal 15 is switched on. A manipulation dot is shown in the LCD display in the event of any discrepancy. The manipulation dot appears to the left of the trip distance recorder on the instrument cluster. The manipulation dot is displayed in the following cases:
- The vehicle identification number stored in the instrument cluster is different to the one stored in the CAS control module.
- A vehicle identification number is not stored in one of the two control modules (e.g. new part).
- The module in the instrument cluster for storing the total distance reading is faulty (the kilometre reading is shown as 999999).

Installing a new CAS control module:
Order the new CAS control module for the specific vehicle in question, quoting model code number, vehicle identification number, standard equipment. Once the new CAS control module has been programmed and encoded (DME/DDE control module and CAS control module mutually identified and calibrated), the engine can be started.

IMPORTANT: Do not install a used CAS control module. The engine cannot be started if the CAS control module being fitted has already been used (different vehicle identification number).

Installing a new instrument cluster:
The tampering dot is set after terminal 15 is switched on because the vehicle identification number is not yet encoded in the instrument cluster. Encode the instrument cluster (input the vehicle identification number in the instrument cluster and assign it to the vehicle). Switch terminal 15 off and on. After terminal 15 has been switched back on: The current kilometre reading and the CBS data are transmitted to the instrument cluster by the CAS. The tampering dot is deleted.

Locking a remote control:
The service function "remote control/lock/enable" in the BMW diagnosis system can be used to lock or enable remote controls, identification sensors or spare keys.

It is recommended that a key is disabled if it is lost or stolen. The engine cannot be started with a disabled remote control. The functions of the remote control buttons are also locked.

A remote control can only be locked if it has been used at least once and has not currently been authenticated by the CAS control module as a valid key.

To run the service function, it is required that CAS control module has currently detected a valid and enabled remote control.

Activating a new remote control:
A new remote control can be used immediately.

If the remote control is a replacement for a lost, stolen or defective remote control, the old remote control still has to be blocked using the service function "block/release remote control". To use the Car/Key functions, the service function "Personalization number" has to be run.

Notes on coding / programming

IMPORTANT: After replacing the CAS control module, it must be programmed and encoded.

No liability can be accepted for printing or other faults. Subject to changes of a technical nature