GF80.57-P-0003GM Drive Authorization System Level 3 (DAS (FBS) 3), Function

GF80.57-P-0003GM Drive Authorization System Level 3 (DAS [FBS] 3), Function

Component Identification:

Function requirements, general
^ C. 30 ON
^ Valid transmitter key inserted into EIS control unit

Drive authorization system, stage 3 (DAS 3), general
The DAS 3 allows the ignition to be switched on and the engine to be started. DAS 3 is a compound system consisting of control modules, each of which calculate and compare the drive authorization code independently. If the check in question is valid, each component is released automatically.

The following control units are integral parts of the DAS 3 system:
- EIS control unit
- ME control unit (N3/10) (with gasoline engine) or CDI control unit (N3/9) (with diesel engine)
- Fully integrated transmission control unit (Y3/8n4) (with transmission 722.9)
- Intelligent servo module for DIRECT SELECT (A80)

The DAS 3 system comprises the following subfunctions:
^ Function sequence for switching c. 15C (transmitter key in position "A")
^ Function sequence for switching c. 15R (transmitter key in position "B")
^ Function sequence for switching c. 15 (transmitter key in position "C")
^ Function sequence for switching c. 50 (transmitter key in position "D")
^ Deactivating circuits

Function sequence for switching circuit 15C (transmitter key in position "A")
When the transmitter key is inserted into the EIS control unit, it switches on the inductive power transmission for power supply to the transmitter key. Encrypted data is exchanged via infrared signals between the transmitter key and the EIS control unit for identification of the transmitter key..

The identification code is computed in dialog between transmitter key and the EIS control unit using the so-called Hash method. The EIS control unit transmits the hash value to the other control units involved.
Check, release and feedback is performed separately by each control unit.

The hash method is single-way encryption which prevents the vehicle from being started with an invalid transmitter key. With this method a new number combination is calculated from the old number combination. It is not possible to calculate vice versa. Number combinations already calculated cannot be calculated again.

The next Hash values are computed in the EIS control unit. After completion of the calculation, the energy transmission is switched off.

After positive identification of the transmitter key the following operations are accomplished:
- Key position recognition switched on
- Waking up interior CAN
- Output of circuit 15C

The vehicle can be started when the battery in the remote control key is discharged.
The function keys of the transmitter key are not active as long as the EIS control unit is inserted
It is not possible to active any terminals with an incorrect transmitter key or a defective transmitter key. The note "Key does not belong to vehicle" appears in the instrument cluster (A1).

Function sequence for switching circuit 15R (transmitter key in position "B")
C. 15R is actuated by turning transmitter key to position "B". The status of c. 15R is output to the interior CAN.

The transmitter can no longer be removed in position "B".

Function sequence for switching circuit 15 (transmitter key in position "C")
C. 15 is actuated by turning transmitter key to position "C". The status of c. 15 is output to engine compartment CAN and interior CAN. Power-intensive consumers are supplied by circuit 15X. Parallel to this, an encrypted DAS 3 request is transmitted to the ME-SFI control unit or CDI control unit, fully integrated transmission control unit and intelligent servo module for DIRECT SELECT.

Function sequence for switching circuit 50 (transmitter key in position "D")
The starter (M1) is actuated via the ME control unit or CDI control unit by turning the transmitter key to position "D".
The status for c. 50 is output to the interior CAN or engine compartment CAN.
C. 15X is removed from the interior CAN and the engine compartment CAN until c. 50 is off again and the engine is running (time control, if applicable).

When circuit 15X is switched off, the electrical consumers are switched off to facilitate starting the engine.
The transmitter key automatically returns to position "C" when released

Deactivating circuits
Turning transmitter key back to left switches off the engine. The following functions are implemented in the EIS control unit:

Transmitter key in position "B"
- Switch off signals c. 15 and c. 15X

Transmitter key in position "A"
- Circuit 15R Off
- Transmitter key can be removed (transmission must be in "park position")

The EIS control unit can request a new check for identification of the transmitter key during restart without removing the transmitter key.

If the communication is interrupted or the EIS control unit or the intelligent servo module for DIRECT SELECT is defective, the emergency path is actuated. The EIS control unit on-board power supply voltage is switched to the emergency path. A spring-loaded actuator is actuated in the intelligent servo module for DIRECT SELECT and the transmission is shifted to the "Park position. The electrical and mechanical system in the intelligent servo module for DIRECT SELECT are synchronized automatically after reproducing the functionality.