The Drive Authorization System (DAS) is the name for the Mercedes Immobilizer system combining vehicle access and drive authorization. Prior to 1996, DAS was separated from the engine control module, and ignition switch operation was based solely on a mechanical key. An early version of DAS was first introduced in approximately 1993 when Mercedes started networking DAS, the engine, transmission, ABS, and traction control systems on a common data bus called CAN.
The Mercedes pneumatic control doorlock system has been in existence since the early 1980s, and although now it is much more advanced, it is still in use today. It steadily became more sophisticated, adding features like central locking, starter lock-out, and steering lockout.
DAS 3 is the most sophisticated and advanced generation of DAS. DAS 3 was introduced on the C, E and CLK class in 1997 and the S class in 1998 (210/208/202), increasing each year with more models phased in. This system has all the same features of DAS 2b except that the ignition switch is now fully electronic (the mechanical key is used only for vehicle access). This means that with DAS 3, both access and drive authorization are fully electronic.
Access authorization using the remote key uses both infrared and radio transmission, but the electronic key drive authorization only uses infrared. The electronic key transfers a radio wave code to the electronic ignition and starter switch (EIS).

With this special function you can read/write AAM and DAS EEPROM data. For Mercedes ML you can program a transponder using the "Key Programming" function. After this you can learn the already programmed transponder to the immobilizer system. Simply specify the key number (it must be between 1 and 8) and press the button "Learn ML Transponder".


Note the following when working on DAS 3 systems:
- The electronic key is completely separate from the remote key access system and does not require the transmitter battery of the remote control. Instead, it is powered by the EIS, which means that the electronic key can be used to start the vehicle even if the remote control battery is dead.
- The side of the electronic key also contains a slide out emergency mechanical key which allows access to the vehicle if the remote battery is dead. It also can be used to lock the glove compartment and the trunk.

From this screen you can access the "DAS Adaptations" screen. It allows to revocably, or irrevocably deactivate/reactivate keys. This function would be useful if, for example, you have lost one of your keys - then you can irrevocably deactivate it.



Also you can access the "Learn Radio Code of a new Transmitter Key" screen. It allows to teach a new remote control transmitter key.