The vehicle immobilizer system consists of the ECM, the SMARTRA3 and ignition keys with built-in transponder.

The ECM carries out the check of ignition key by special encryption algorithm with SMARTRA3 and Transponder.

The encryption algorithm (between ECM and SMARTRA3) is the one offered from BOSCH.

The encryption algorithm (between ECM and Transponder) is Hitag type 2 which is a high level system. With IGN On, the ECM executes the key Authentication after SMARTRA3 authentication. The Engine can be started when the key authentication is confirmed by the SMARTRA3.

The Key teaching procedure starts with ECM request of PIN from Scanner. The "virgin“ ECM stores the PIN and the key Learning can be started. The "learnt“ ECM compares the PIN from tester with the vehicle password in Transponder. If the data are correct, the key Learning can be started.

Scanner requests the Learning of the first key, the SMARTRA3 is registered at first and then the first key is registered by ECM. If the SMARTRA3 status is learnt and PIN number is different, the SMARTRA3 will return the incorrect PIN data to the ECM. In this case, The ECM can’t excute the key learning process.

The ECM sets DTC P1675 if characteristic data of transponder doesn't coincide with that of ECM owing to transponder programming error.

Fig.1) A normal signal waveform of antenna and immobilizer communication when IG key(TP : Transponder) is OFF to ON.