GF80.57-P-0003SK Drive Authorization System Stage 3 (DAS 3), Function

GF80.57-P-0003SK Drive Authorization System Stage 3 (DAS 3), Function

Component Identification:

Overall description
The drive authorization system stage 3 (DAS 3) is a system combination of control units consisting of:
^ EIS control unit (N73),
^ Electric steering lock control unit (N26/5),
^ ME-SFI control module (N3/10) and
^ Fully integrated transmission control (VGS) control unit (Y3/8n4).

Encrypted data is exchanged between the transmitter key (A8/1) and the EIS control unit (N73) over infrared. The code is computed in dialog between transmitter key (A8/1) and the EIS control unit (N73) using the Hash method.
The corresponding Hash value of the transmitter key (A8/1) is transmitted to the control units (N73, N26/5, N3/10 and Y3/8n4) by the EIS control module (N73).Checking, release and feedback is performed separately by each control unit (N73, N26/5, N3/10 and Y3/8n4)

Hash function
The encrypted base module of the drive authorization system, stage 3 (DAS 3) is a so-called Hash function. The most important property function of the Hash function is the one-way characteristic. This means that another number can be calculated using the Hash function from an initial number, however that calculation of the initial number in the opposite order is practically impossible.

Function
When inserted into the EIS control unit (N73), the power supply to the transmitter key (A8/1) is established inductively via a coil in the EIS control unit (N73) so that the vehicle can be started even when the transmitter key (A8/1) battery is discharged.
Mutual infrared communications occur between the transmitter key (A8/1) and the EIS control unit (N73).

The function buttons of the transmitter key (A8/1) are not active as long as it is inserted in the EIS control unit (N73).

Transmitter key (A8/1) in position "A"
^ The inductive energy transmission to the voltage supply of the transmitter key (A8/1) is switched on.
^ Encrypted data exchange between transmitter key (A8/1) and EIS (N73) control unit for identification.

The next Hash values are calculated in the EIS control unit (N73). After completion of the calculation, the energy transmission is switched off. After positive identification, the following is performed:
^ Release of solenoid for rotary lock in EIS control unit (N73) for transmitter key (A8/1).
^ Switch-on of key position recognition.
^ Wake-up of CAN-B (CAN-B).
^ Output of c. 15C.
^ Encrypted data exchange between EIS control unit (N73) and electric steering lock control unit (N26/5) for identification.Following successful communication, the steering lock is unlocked by the electric steering lock control unit (N26/5) and secured.

Transmitter key (A8/1) in position "B"
^ Actuation of c. 15R.
^ Output of status of c. 15R to CAN-B (CAN-B).

The transmitter key (A8/1) cannot be removed in position "B".

Transmitter key (A8/1) in position "C"
^ C. 15 is actuated.
^ Output of status c. 15 to CAN-B (CAN-B) and CAN-C (CAN-C) as well as c. 15X to CAN-B (CAN-B).
^ Encrypted request for ME-SFI control unit (N3/10)
^ Encrypted request for fully integrated transmission control (VGS) control unit (Y3/8n4)
^ Data output transmitted from CAN-C (CAN-C) to CAN-B (CAN-B).
^ Data output transmitted from CAN-B (CAN-B) to CAN-C (CAN-C).

The transmitter key (A8/1) cannot be removed in position "C".

Transmitter key (A8/1) in position "D"
^ Actuation of starter via ME-SFI control module (N3/10).
^ Output of status of c. 50 to CAN-B (CAN-B) and CAN-C (CAN-C).
^ C. 15X is removed from CAN-B (CAN-B) until c. 50 is off again and the engine is running (c. 61).

The transmitter key (A8/1) automatically returns to the position "C" when released

Take vehicle out of operation
Turning the transmitter key (A8/1) back to the left switches off the engine.
The following functions are realized in the EIS control unit (N73):

Transmitter key (A8/1) in position "B"
^ Switch off signals c. 15 and 15X
^ Set CAN-C (CAN-C) communication

Transmitter key (A8/1) in position "A"
^ Steering lock is locked by the electric steering lock control unit (N26/5).
^ Open load switch c. 15R.
^ Transmitter key (A8/1) can be removed (on vehicles with transmission 722, the selector lever should be in position "P").

The EIS control unit (N73) can request a new identification check of the transmitter key (A8/1) without removing the transmitter key (A8/1) during restart.