EWS III (3.2) system operations.

The starting sequence for the EWS III (3.2) is as follows:
• The key is inserted into the lock cylinder and switched (ON). The EWS III control module is powered through KL R and sends a 125 kHz AM signal to the ring antenna. The AM signal induces voltage in the key coil and powers up the transponder.
• Powered up, the key transponder sends the key identification code to the EWS III module.
The EWS III module verifies the key identification code and checks to see if the key is enabled. If the key is correct and enabled, a password is sent to the transponder over the 125 kHz AM signal through the ring antenna.
• When the transponders accepts the password, it releases the changing code, which it received from the EWS III module during the last start-up operation, to the EWS III module via the ring antenna.
• The EWS III module compares the changing code received from the transponder with the code stored in its memory and if they match the process is allowed to continue.
The EWS III module looks at the other inputs for correct status (e.g. Code function not active, Transmission in P or N or clutch depressed, engine speed below specified RPM) and energizes the internal relay to begin starter operation.
• As the starter begins to operate, the EWS III module sends the ISN to the DME and if verified as correct by the DME, drive away protection is cancelled and injection and ignition is enabled. The EWS III module also sends a new changing code to the key transponder through the ring antenna.

 

is one of the best Professional scan tools to for BMW; Autohex Scanner can test BMW Systems effectively and easily, with many powerful features to help you in diagnosing and testing. For more information: BMW Scan Tool