Drive authorization system stage 4 (DAS 4) function

P80.57-2327-81

 Start enable using the transmitter key is described below.

P80.57-2252-01

Function requirements, general

 Circuit 30 ON

 Valid transmitter key

Drive authorization system, stage 4 (DAS 4), general

DAS 4 allows the ignition to be switched on and the engine to be started. DAS 4 is a compound system consisting of control units, each of which calculate and compare the drive authorization code independently. If the comparison is valid, the system is released.

The following control units are integral parts of the DAS 4 system:

 Electronic ignition switch control unit

 CDI control unit or ME-SFI [ME] control unit

 Drivetrain control unit

 Electric steering lock control unit

 Fully integrated transmission control control unit

 Power electronics control unit

 Electric machine

DAS [FBS] 4 comprises the following subfunctions:

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

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

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

 Function sequence for switching circuit 50 (transmitter key in position "D" (start engine))

 Function sequence for deactivating circuit

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

When the transmitter key is inserted into the electronic ignition lock control unit, it switches on the inductive power transmission (power supply to the transmitter key). The transmitter key and the electronic ignition lock control unit exchange encrypted data for identification of the transmitter key.

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

 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. Number combinations already calculated cannot be calculated again.

After end of communication, the electronic ignition lock control unit switches off power transmission to the transmitter key.

If the transmitter key was identified as valid, the following occurs  :

 Waking CAN and chassis FlexRay

 Output of circuit 15C

The electronic ignition lock control unit then sends the "Drive authorization prompt" signal over the chassis FlexRay, powertrain control unit and the engine CAN to the CDI control unit or the ME-SFI [ME] control unit and with transmission 722, 724, 725 over the chassis FlexRay, powertrain control unit and the drive train CAN to the fully integrated transmission control unit.

On transmission 716, the electronic ignition lock control unit directly transmits the signal "Drive authorization request" to the electric steering lock control unit.

For hybrid vehicles, the electronic ignition lock control unit transmits the "query for driver authorization" signal to the electric machine via the suspension FlexRay, the powertrain control unit, the hybrid CAN, the power electronics control unit, and the direct line.

Check, release and feedback is performed separately by each control unit. The signal flow to the electronic ignition lock control unit is accomplished in opposite direction.

If a valid transmitter key is identified, a message is output in the instrument cluster. The electronic ignition lock control unit transits the request to display this message to the instrument cluster via the interior CAN.

 The vehicle can be started when the battery in the transmitter key is discharged.
The buttons on the transmitter key are not active as long as the electronic ignition lock control unit is inserted.

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

If the transmitter key is turned to position "B", the electronic ignition lock control unit sends the circuit 15R status directly or indirectly over all the CAN buses and the chassis FlexRay.

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

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

When the transmitter key is in position "C", the electronic ignition lock control unit transmits the circuit status of circuit 15 and the circuit status of circuit 15X directly or indirectly to the electronic ignition lock control unit (transmission 716) via all CAN buses and chassis FlexRay as well as via a direct line.

Parallel to this, an encrypted DAS 4 query is sent to the electronic ignition lock control unit.

 15XBy transmitting the circuit status of circuit the electronic ignition lock control unit enables switch-on of the high-current loads.

Function sequence for switching circuit 50 (transmitter key in position "D" (start engine))

If the transmitter key is turned to position "D", the electronic ignition lock control unit sends the circuit 50 status over all CAN data buses and the chassis FlexRay.

As soon as the electronic ignition lock control unit sends the circuit 50 status, the circuit 15Xstatus is then discontinued.

The CDI control unit and ME-SFI control unit receives the circuit status of circuit 50 via chassis FlexRay, drive train control unit and engine CAN and starts the engine.

 If circuit status of circuit 15X fails, all high-load electrical consumers are switched off to ensure sufficient power to start the engine.
The transmitter key automatically returns to position "C" when released.

Function sequence for deactivating circuit

If the transmitter key is turned to left, the engine is switched off. The electronic ignition lock control unit cancels the circuit status accordingly:

 Transmitter key in position "B"

 Circuit 15 and circuit 15X OFF

 Transmission attempts to shift automatically to position "P" (Transmission 722, 724, 725)

 Transmitter key in position "A"

 Circuit 15R OFF

 The transmitter key can be removed and the transmission shifted automatically to position "P" (Transmission 722, 724, 725)

 Circuit 15C remains activated when the transmitter key is inserted. The electronic ignition lock control unit can request a new check for identification of the transmitter key during restart without previously removing the transmitter key.