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 troubleshootingTrouble in passenger airbag on / off indicator
Description
The occupant classification system detects the front passenger seat condition
and then indicates whether
the front passenger airbag is activated or not through the passenger airbag on /
off indicator
illumination.
The passenger airbag on / off indicator illumination changes dep ...
Terminals of ecu
Center airbag sensor assembly (w/ curtain
shield airbag)
Center airbag sensor assembly (w/o curtain
shield airbag)
...
Door courtesy switch circuit
Description
The main body ecu detects the condition of the door courtesy switch.
Wiring diagram
Inspection procedure
Read value of intelligent tester (door courtesy light switch)
Connect the intelligent tester (with can vim) to the
dlc3.
Turn the ignition switch to the on positi ...