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 troubleshootingOnly passenger door lock / unlock functions do not operate
Description
The main body ecu receives lock / unlock switch signals and activates the
door lock motor accordingly.
Wiring diagram
Inspection procedure
Read value of intelligent tester (lock position switch)
Use the data list to check if the door lock is
functioning properly.
...
Transmission fluid temperature sensor "A" performance
Description
Refer to dtc p0710 (see page ax-46).
Monitor description
This dtc indicates that there is a problem with output from the atf
temperature sensor and that the
sensor itself is defective. The atf temperature sensor converts the atf
temperature to an electrical
resistance v ...
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 ...