Key with Transponder

Four keys are initially supplied with each vehicle. Each key contains a wireless electronic chip (transponder chip). The function of the transponder is to receive and transmit data to the EWS II control module. The transponder contains a wireless read/write EEPROM in addition to a small capacitor and coil for self power capabilities.

Fig 1: Identifying Key With Transponder

Courtesy of BMW OF NORTH AMERICA, INC.

The functions of the EEPROM are:

• Store codes for key identification, password and changing codes.
• Receive and respond to coded messages from the EWS II control module.

Power for the transponder is produced through the inductive coil and stored in the capacitor. Each time the key is inserted into the ignition AC voltage in the antenna ring induces voltage in the inductive coil.

Fig 2: Identifying Inductive Coil In Key

Courtesy of BMW OF NORTH AMERICA, INC.