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 troubleshootingShort in front passenger side - side squib circuit
Description
The front passenger side - side squib circuit consists of the center airbag
sensor and the front seat side
airbag rh.
The circuit instructs the srs to deploy when the deployment conditions are met.
These dtcs are recorded when a malfunction is detected in the front passenge ...
Brake switch "B" circuit high
Description
The purpose of this circuit is to prevent the engine from stalling while
driving in the lock-up condition when
the brakes are suddenly applied.
When the brake pedal is depressed, this switch sends a signal to the ecm. Then
the ecm cancels the
operation of the lock-up clutch ...
Cold start
Description
The electronic throttle control system (etcs) controls the engine idling
speed. The etcs operates the
throttle actuator to open and close the throttle valve, and adjusts the intake
air amount to achieve the
target idling speed.
In addition, the ecm retards the ignition timi ...