What is Car Access System in BMW:
The Car Access System is a module mounted inside BMW cars, it controls the accessibility of the car by keeping a tight rein over the master functions of the central locking system, it was designed to have encryption software for BMW cars. It is also responsible for the ignition of the engine. Apart from this, it also helps in controlling the terminal statuses (KL R, KL 15, KL 50) by means of controlling the start/ignition button.
The Car Access System is a new feature introduced in the recent models of BMW (those introduced after 2002 and mainly E65) and has been integrated from a number of previous separate components (or control units) like Electronic Vehicle Immobilization (EWS), Ignition or the Starter Switch and functions of the central body electronics (ZKE). This integration has been done in the wake of the rise of car thefts as in the European Union countries and as per the guidelines set by the European Insurance Commission. This system is also called the Drive Away Protection System. Its prototype incorporated a circuit into the DME from the general module.
The software inside the CAS is secured by strong Algorithms to ensure the security of BMW cars, it is using RSA, CRC32, and MD5 Algorithms.
The Car Access System regulates the key features of the automobile as enlisted below:
- The electronic car immobilizer
- The power windows
- The central locking system
- The electronic steering lock
- The comfort start access system
- Remote operations system
- The Gateway module for K-CAN.
The Electronic Car Immobilization System: The Electronic Car Immobilization System makes the driving experience much easier for you and your loved ones. It is an advanced security feature which makes sure that the driver has used the remote control to access the engine or has at least put in the key in the respective slot. Only then does it allow a smooth start up of the engine.
The Comfort Start Feature: This feature helps in an operator-friendly ignition of the car’s engine. This is achieved by means of keeping the starter motor on till the engine is fired-up.
The Central Locking System: The car operating system, as mentioned above, is in charge of the Central Locking System. This means that after an operating request is received from the driver of the car by means of the remote control system, center lock button or the lock contact, the CAS decides whether it will unlock the Central Locking System or it will lock or even secure it. This bit of information is transmitted to the corresponding command system through the K-CAN data buses (consisted of the K-CAN SYSTEM and K-CAN PERIPHERIE) to the control units. This is specifically an anti-theft measure undertaken by the engineers at BMW.
The Remote Control Unit: The remote control uses a radio transmitter to perform its various functions and respond to the Central Locking System. The radio transmitter uses random codes to encrypt the received data up to 4 remote sets to stem out manipulations. The CAS receives these radio signals from the rear aerial window.
Now there is a personalization number stored in the remote control unit which gets transmitted along with the encrypted code. This number has a specific coded settings attached to its Key Memory on which the car settings also depend.
Terminal Control: The terminals R & 15 along with the data bus activation cable are controlled by the CAS.
Power Window Control: The convenience tools, power window including the child safety lock settings are stored in the CAS.
Gateway Module for K-Can: The BMW CAS internal Software connects and operates between the two buses fitted in the car- the K-CAN SYSTEM and K-CAN PERIPHERIE. In the event of a short circuit, the latter can be fitted in the place of the car. It also decreases bus load significantly.
CAS Security Break:
The CAS supposed to protect the vehicle from being stolen, However this security restrict car owners and BMW independent workshops from replacing the CAS if it got defected, they cannot change the ECM (engine control module), and they cannot make a spare key.
All these tasks must be required from BMW Authorised dealer, and he will order the module or key from BMW, usually this take 15-30 days, actually this is not a solution if the car has no working key, or one of the modules is corrupted.
So, this is a long solution, is there a BMW software that can help for make procedures faster?
BMW workshops use very special engineering tools (BMW Software) to break the CAS security and modify the records that should be modified to accept a new key or to replace the ECM, or even replace the CAS.
One of the well know BMW Software that is able to replace the CAS, DME, as well as add a new BMW key is Autohex II, it supports all versions and generations of CAS from 2002 up to date, more information about this tool from Microtronik website, BMW Software
They also have a supporting forum you can check it here: http://www.microtronik.com/forum/