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 troubleshootingBrake 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 ...
Front console illumination
On-vehicle inspection
Inspect front console illumination
Connect the battery's positive (+) lead to terminal 1
and the negative (-) lead to terminal 2, then check
that the light comes on.
Ok:
light comes on.
If the result is not as specified, replace the front
console illumin ...
Pressure control solenoid "d" electrical (shift solenoid valve slt)
Description
Refer to dtc p2714 (see page ax-91).
Monitor description
When an open or short in the shift solenoid valve slt circuit is detected,
the ecm interprets this as a fault.
The ecm will illuminate the mil and store the dtc.
Monitor strategy
Typical enabling conditions
...