Comfort start with immobilizer function.

(CAS) control unit

Car Access System (CAS)
The Car Access System (CAS) control unit contains the functions of the radio remote control, the ignition switch, the terminal control, the immobilizer and the starter motor control. It is also the gateway module between the data buses K-CAN SYSTEM and K-CAN PERIPHERALS.
The start-stop button and the ignition lock are integrated in the CAS.
In addition, the CAS contains the data for the EWS random code (EWS: electronic vehicle immobilization system) that is sent to the engine control unit on starting up.
The CAS controls terminal 15 for all electrical systems. In addition, with terminal R on, the information (Terminal R on) is transmitted via the data buses to the control units.
The CAS also activates terminal 15 wake-up for all control units of the PT-CAN Activation of the terminal 15 WUP has the effect that the control units are shifted from sleep mode to operating mode.
In the starting process, terminal 50L for the comfort start relay and terminal 50E for the start request are switched to the engine control unit.

Remote control and spare key
The remote control contains the data for the electronic vehicle immobilization system (EWS) and the radio remote control. An accumulator is integrated for the power supply. The accumulator is charged when the remote control is engaged in the ignition lock.
For mechanical emergency actuation in the case of failure of the central locking system, a mechanical key is inserted in the remote control. However, this mechanical key contains no EWS data.
As emergency key, a mechanical spare key is supplied; this also contains a data memory for the EWS data (transponder). The spare key can be inserted in the ignition lock in the CAS using an adapter.

Engine control unit (DME)
The engine control unit controls and monitors all the functions of the engine. It also controls the ignition and the fuel injection.
The data for the EWS random code is also stored in the engine control unit. The EWS data is transmitted between the CAS and DME across the data line D-EWS.

Brake-light switch
The brake-light switch is an electronic switch that records operation of the brake pedal. Two switches are integrated in the switch housing: the actual brake-light switch and the brake-light test switch. This enables function monitoring of the switch.
An engine start-up is only possible when the brake pedal is pressed. For reasons of safety, the CAS control unit evaluates both the signal of the brake-light test switch and the switch signal across the data bus K-CAN SYSTEM.

Light module (LM)
The light module controls and monitors the vehicle lights. Information is received and sent via the data bus K-CAN SYSTEM.
The light module registers the signal of the brake-light switch and routes it across the data bus to other control units.

Dynamic stability control DSC
The DSC control unit contains the functions of the anti-lock braking system ABS and driving dynamics control.
The DSC control unit is connected to the PT-CAN data bus.
When the brake is pressed, the DSC control unit sends a signal across the data bus to the effect that brake pressure has been set up. The CAS uses this information, which means that even if the brake-light switch fails an engine start-up is possible.

Electronic Gearbox Control (EGS)
The EGS control unit controls and monitors the functions of the automatic transmission. It is connected to the PT-CAN data bus.
An engine start-up is only possible when the gearbox is in park position (selector-lever position P) or neutral position (selector-lever position N). The gearbox control unit transfers the selector-lever position across the data bus. For reasons of safety, there is also a line between the gearbox control unit and the CAS control unit (line name P). Positive (battery voltage) is switched across this line when the selector lever is at P or N.

Central Gateway Module (ZGM)
The central gateway module links the data buses
· BYTEFLIGHT
· K-CAN SYSTEM
· PT-CAN
· Diagnosis bus

 

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