Key Recognizing Principle

The Immobilizer system is based on the recognizing of the key before each cranking request (inserting the key into the steering lock), by way of an inductive link between the transponder device (integrated in the key head) and the vehicle (toroidal coil placed around the steering lock and wired with the BCM).

Fig 1: Identifying Antenna Position

Courtesy of KIA MOTORS AMERICA, INC.

Key recognizing is based on a challenge/response principle with an encryption algorithm whose parameter is a secret key (KTR). The algorithm is determined by the transponder supplier.

There is one and only one secret key for each vehicle. The secret key is generated during the first key teaching in the car production line. It must be saved in the non-volatile memory of the BCM and the transponder, associated to the vehicle identification number (VIN) of the production line.

NOTE: The Special equipment in Car Production line will produce " Vehicle Secret Code" (PIN code) which is induced from " Vehicle Serial Identification Number". This " Vehicle Secret Code" (PIN code) allows the teaching of new keys and BCM and/or keys replacement

When the BCM learns this " Vehicle Secret Code" (PIN code), two other codes are determined during the first key teaching.

The KTR secret key
The VIN-code, used in the communication between