Car access system (CAS)

Functional description, see BMW Technology:

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Service functions

Replacing control modules

The following points must be borne in mind when the CAS or the engine control module are replaced:

• If a CAS control module is replaced, it must be ordered using the vehicle identification number (VIN). Following installation, that starting value must be matched to the engine control module. This starting value match is performed using the service function ”DME/DDE - CAS calibration” in the BMW diagnosis system.
  
• If the engine control module is replaced, the drive-enable code must be transferred from the CAS to the engine control module following installation. This operation is also performed using the service function ”DME/DDE - CAS calibration” in the BMW diagnosis system.
  
• After the calibration of the EWS and engine control module, these are mutually linked. It is not possible to replace one of the two control modules as a test.
  

DME/DDE - CAS calibration

In the case of a new engine control module, the service function ”DME/DDE - CAS calibration” in the BMW diagnosis system is used to read the EWS drive-enable code from the CAS and transfer it into the engine control module. This means that the engine control module and the CAS control module are mutually linked.

If the engine control module is already linked to the CAS, the service function is used to perform a starting value match. This means that the random code calculation between the CAS and the engine control module is calibrated.

A start match is required if there is a variance in the random codes caused by the influence of faults in the two control modules.

As of EWS4, a start calibration is no longer required.

Locking the remote control/spare key

The service function ”Disable/enable remote control/key” in the BMW diagnosis system can be used to disable or enable remote control keys or spare keys.

It is recommended that a remote control key is disabled if it is lost or stolen. With a disabled remote control key (or spare key) the engine can not be started. The functions of the remote control are also disabled.

A remote control key or spare key can only be disabled if the remote control key or spare key has been used at least once and is currently not inserted in the ignition lock.

To run the service function, it is required that a valid and enabled remote control key or a valid and enabled spare key is detected in the ignition lock.

Activating of a new remote control

Insert the new remote control in the slot and hold in this position until the remote control locks into place. This can take up to ten seconds. After locking, wait another five seconds. The remote control is then ready for use.

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