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 troubleshootingDiagnosis system
Check dlc3
The ecm uses iso 15765-4 for communication. The
terminal arrangement of the dlc3 complies with sae
j1962 and matches the iso 15765-4 format.
If the result is not as specified, the dlc3 may have a
malfunction. Repair or replace the harness and
connector.
Hint:
Conn ...
Rear airbag sensor
Components
On-vehicle inspection
Check rear airbag sensor (vehicle not
involved in collision)
Perform a diagnostic system check (see page rs-
49).
Check rear airbag sensor (vehicle
involved in collision and airbag has not
deployed)
Perform a diagnostic system check ...
Diagnosis system
Check dlc3
Check the dlc3:
the power steering ecu uses can (iso11898-1)
and iso9141-2 for communication protocol. The
terminal arrangement of the dlc3 complies with
sae j1962 and matches the iso9141-2 format.
Notice:
*: Before measuring the resistance, leave the
vehicle ...