The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingProblem symptoms table (2005/11-2006/01)
Hint:
Use the table below to help determine the cause of the
problem symptom. The potential causes of the symptoms are
listed in order of probability in the "suspected area" column of
the table. Check each symptom by checking the suspected
areas in the order they are listed. Replace p ...
Removal
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove generator assembly
Remove the generator assembly from the vehicl ...
Removal
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove no. 1 Engine under cover
Remove front fender apron rh
Remove radia ...