Main functions of Comfort start with immobilizer

Engine start
The overall sequence for starting the engine can be described as follows:
The remote control is inserted in the ignition lock.
· A ring coil in the CAS control unit feeds current to the data memory in the remote control and the EWS data is read. If the remote control is a valid and enabled key that belongs to the vehicle, it is locked in position in the ignition lock.
· After this locking, the CAS sends the command (terminal R on) across the data buses. This activates a number of control units.

Pressing the start-stop button
When the start-stop button is pressed, terminal 15 is activated first of all.
· Activating of the four outputs, terminal 15 in the CAS. The relief relay for the ignition coils is switched on via terminal 15-3.
· Activation of the three outputs terminal 15 WUP (wake-up) in the CAS.
On activation of the outputs terminal 15 WUP (wake-up), all the control units connected to the PT-CAN data bus are activated.

When the start-stop button is pressed, the CAS checks whether the brake pedal is pressed and the gear selector lever is at P or N. If this condition is met, the engine is started:
· Across the line terminal 50E, the CAS switches a positive (battery voltage) at the DME control unit, signaling that the engine is to be started.
· Across terminal 50L, the CAS switches a positive (battery voltage) at the comfort start relay. The starter motor is switched on.
· Via the data line D-EWS; a random code of EWS is transferred to the DME control unit.
· The engine control unit compares the transmitted random code with the calculated code. If they match, the ignition and the fuel injection are enabled.
· The starter motor turns until the CAS control unit receives the signal (Engine running) from the engine control unit via the data bus. Then, the terminals 50 in the CAS are switched off.
If the engine does not start, terminals 50 are deactivated after a maximum of 20 seconds and the engine start is aborted.
 

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