Operation CHARM: Car repair manuals for everyone.
Hosted by mcallihan.com

Key Identification and Start Procedure



Key identification and start procedure
The following procedure takes place after inserting the vehicle key in the ignition lock:

The transponder in the key is powered via the loop antenna and sends the key data to the EWS3 control unit.

- The EWS3 control unit then checks the key data to ensure it is correct and only then sends an enable signal to the engine management system and starter.
- After the engine has started, the EWS3 control unit generates new key data (change code) and transfers them to the transponder in the key.
- A new variable code is also created and stored in the DME/DDE control unit.