Benzworld.org - Mercedes Benz Discussion Forum - View Single Post

MarJa · 09-23-2004, 03:01 AM

Randy,

Immobilizer or Driver Authorization System (DAS) - All M-Class vehicles (or at least the 98) are equipped with the Driver Authorization System controlled by the All Activity Module through a CAN bus that communicates with the ME-SFI control module.

At each start attempt, the AAM and ECM exchange codes. The AAM approves of fuel enabling by the ECM only if it recognizes a valid key code in the ignition system. With an invalid code, the starter may operate, but the engine will not be allowed to start.

DAS uses an ignition key module containing a transponder (EEPROM memory) in which a fixed and rolling access code is written. This code is read by the AAM and compared with the code stored in the AAM. If the AAM recognizes the code as "correct," it creates a new rolling code and writes it into the transponder of the key. In this way the code always changes to provide engine starting only with the "correct" key.

The AAM generates a new rolling code every time the system recognizes a valid key in the ignition switch.

Also, make sure the key batteries are good.

09-23-2004, 03:01 AM	#8 (permalink)
MarJa BenzWorld Junior Member Date registered: Apr 2004 Vehicle: 98 ML320 Location: Pennsylvania Posts: 43	RE: HELP! Changed battery and .... Randy, Immobilizer or Driver Authorization System (DAS) - All M-Class vehicles (or at least the 98) are equipped with the Driver Authorization System controlled by the All Activity Module through a CAN bus that communicates with the ME-SFI control module. At each start attempt, the AAM and ECM exchange codes. The AAM approves of fuel enabling by the ECM only if it recognizes a valid key code in the ignition system. With an invalid code, the starter may operate, but the engine will not be allowed to start. DAS uses an ignition key module containing a transponder (EEPROM memory) in which a fixed and rolling access code is written. This code is read by the AAM and compared with the code stored in the AAM. If the AAM recognizes the code as "correct," it creates a new rolling code and writes it into the transponder of the key. In this way the code always changes to provide engine starting only with the "correct" key. The AAM generates a new rolling code every time the system recognizes a valid key in the ignition switch. Also, make sure the key batteries are good.