Drive authorization system level 3 (DAS [FBS] 3), function - GF80.57-P-0003LE

Model 221.0 /1, 216.3 as of model year 09 /YoM 08

Positions of the transmitter key (A8/1) in the EZS control unit (N73):

Fig 1: Transmitter Key Positions (A8/1) In EZS Control Unit (N73)

Courtesy of MERCEDES-BENZ USA

Function requirements, general

Circuit 30 ON
Valid transmitter key inserted into EZS 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 units, 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:

EZS control unit
ME-SFI control unit (N3/10) (with gasoline engine) or CDI control unit (N3/9) (with diesel engine)
EGS control unit (N15/3) (with transmission 722.6) or 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 circuit 15C (transmitter key in position "A")
Function sequence for switching circuit 15R (transmitter key in position "B")
Function sequence for switching circuit 15 (transmitter key in position "C")
Function sequence for switching circuit 50 (transmitter key in position "D")
Deactivating circuits
Keylock function

Function sequence for switching circuit 15C (transmitter key in position "A")

When the transmitter key is inserted into the EZS 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 EZS control unit for identification of the transmitter key.

The identification code is computed in dialog between transmitter key and the EZS control unit using the so-called Hash method.

The EZS control unit transmits the hash value of the transmitter key to all other control units involved.

Check, release and feedback is performed separately by each control unit.

Hash function:

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 EZS control unit. After completion of the calculation, the energy transmission is switched off. After positive identification the following is performed:

Key position recognition switched on
Waking up interior CAN
Output of circuit 15C

The vehicle can also be started when the batteries of the transmitter key are discharged.↓

The function keys of the transmitter key are not active as long as the EZS control unit is inserted

If an invalid transmitter key is used, the message "Key does not belong to vehicle" is indicated in the instrument cluster (A1).

Function sequence for switching circuit 15R (transmitter key in position "B")

Circuit 15R is actuated by turning transmitter key to position "B". The status of circuit 15R is output to the interior CAN.

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

Function sequence for switching circuit 15 (transmitter key in position "C")

Circuit 15 is actuated by turning transmitter key to position "C". The status of circuit 15 is output to chassis 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, electronic transmission control unit or 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 circuit 50 is output to the interior CAN or chassis CAN.

Circuit 15X is removed from the interior CAN and the chassis CAN until circuit 50 is off again and the engine is running (time control, if applicable).

When circuit 15X is switched off, all 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 EZS control unit:

Transmitter key in position "B"

Switch off signals circuit 15 and circuit 15X

Transmitter key in position "A"

Circuit 15R Off
Transmitter key can be removed when removing the transmitter key, the transmission is shifted to position "P")

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

Keylock function

The EZS control unit transmits the request to the intelligent servo module for DIRECT SELECT for the transmission to automatically shift to the "Park position" when

The transmitter key is removed from the EZS control unit
The driver or front passenger door is opened (only with code (889) Keyless-Go)

Then the intelligent servo module for DIRECT SELECT shifts the transmission to the "Park position".

If the communication is interrupted or the EZS control unit or the intelligent servo module for DIRECT SELECT is defective, actuation is accomplished over the emergency path. The EZS control unit onboard 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.

	Drive authorization system, stage 3 (DAS 3), location of components		GF80.57-P-0003-01LE
	Electrical function schematic for drive authorization system (DAS)	Model 216	PE80.57-P-2050-97CAB
	Drive authorization system, stage 3 (DAS 3), block diagram		GF80.57-P-0003-02LE
	Component description for intelligent servo module for DIRECT SELECT	A80 Transmission 722.6	GF27.19-P-4020ACS
		Transmission 722.9	GF27.19-P-4020AHS
ME-SFI [ME] control unit, component description		Engine 272	GF07.61-P-6000MIS
ME-SFI [ME] control unit, component description		Engine 273	GF07.61-P-6000MLS
	Component description for electronic transmission control unit	N15/3 Transmission 722.6	GF27.60-P-5164ACS
	EZS control unit, component description	N73	GF80.57-P-6003LE
	Component description for fully integrated transmission control unit	Y3/8n4 Transmission 722.9	GF27.60-P-5165AHS