The immobilizer system consists of a passive challenge-response (mutual authentication) transponder inside the key head, the encoded SMARTRA3 unit / key and the ECM can decode the secret code stored in the SMARTRA3.

The ECM carries out the immobilizer function, the SMATRA3 management and the key management. The immobilizer function is the unlocking of ECM only after detection of a valid ignition key/ the SMATRA3 and the locking of ECM after switching off the engine. The ECM communicates the encoded messages to the SMARTRA3 via a dedicated communication line and confirms the key with the SMARTRA3.

The ECM related to immobilizer has the 3 kinds of software. At the first IGN on, the ECM concludes the software of each option (smart key, non-encoded SMARTRA3, encoded SMARTRA3) by communication. It is called “The autodection for ECM”The PCM/ECM keeps the previous option before being neutral when it is setted to each option.

The ECM sets DTC P1610 if Non Immobilizer EMS is installed on vehicle equipped with Immobilizer.

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