EWS Functions
The EWS function is also integrated into the CAS control unit. The transponder authentication is similar to the method used by EWS 3.3. The encoding process was changed compared to that of the previous versions (to increase security against tampering).
After a start request from the start/stop button, starting may continue if the following conditions are met:
- Valid transponder detected
- Brakes actuated
- Selector lever in position P or N
The EWS sends a message (ISN) with a random code to the DME. To start the engine, the DME (ECM) enables the ignition and fuel injection. The fuel pump is actuated via the SBSR (satellite B-pillar right) as soon as a corresponding speed signal is sent on the bus by the DME (ECM).
The starter is actuated independently of the EWS ISN using the terminal 50 signal. If the starter turns and the engine fails to start, there may be a problem with communication between the DME (ECM) and EWS.