EWS II Operation

STARTING PROCEDURE







When the key is inserted into the lock cylinder and switched "ON", the transmitter/receiver module is powered. The coil and correspondingly the transponder chip are also powered by the induced voltage. Data transfer now takes place between the transponder chip and EWS II control module.

1. The key identification code stored in the EEPROM of the key is sent to the Transmitter/Receiver module.
2. The Transmitter/Receiver module converts the amplitude modulated signal to a digital signal containing the same identification code. The code is sent to the EWS Control Module over the data link.
3. The EWS II control module must recognize the code as valid before the starting procedure will continue.
4. Once the identification code is accepted as valid the EWS II sends the digital password to the Transmitter/Receiver module.
5. The Transmitter/Receiver module converts the signal into an AM signal and sends it to the transponder.
6. If the transponder accepts the received password as valid the sequence continues.







7. With acceptance of the password, the transponder releases the changing code.
8. The code is converted to a digital changing code and sent to the EWS control module.







9. If the code is valid the EWS control module completely accepts the key and the starting procedure continues.







Once the identification and verification of the data codes is complete, the EWS II sends a new changing code to the key for the next starting procedure. By "changing" this code with each starting cycle, the security of the system is enhanced. The changing code is a random number that is generated by the EWS II control module. The transponder stores this code until the next time the ignition is switched on.

Once the key is accepted as valid, the EWS II activates the internal starter relay and the starter circuit is energized.

At the same time the EWS II sends the Individual Serial Number (ISN) code to the DME.

If the ISN code matches the code stored in the DME, the drive away protection is cancelled and the vehicle will start.

The data communication required for engine starting as described above takes place in milliseconds. The vehicle operator will not detect any delay in vehicle starting.