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 troubleshootingDriver side - side airbag sensor circuit malfunction
Description
The side airbag sensor lh consists of part including the diagnostic circuit
and the lateral deceleration
sensor.
When the center airbag sensor receives signals from the lateral deceleration
sensor, it determines
whether or not the srs should be activated.
Dtc b1620/21 is ...
Ecm communication circuit malfunction
Description
The circuit is used to send trc and vsc control information from the skid
control ecu to the ecm, and
engine control information from the ecm to the skid control ecu.
Inspection procedure
Hint:
Check that the part numbers of the installed ecm and skid control ecu are
cor ...
Fail-safe chart
If a problem occurs in the electric power steering system, the
p/s warning light will come on in the combination meter and
steering power assist will be stopped, fixed at a particular
point, or decreased simultaneously to protect the system.
Hint:
The amount of power assist may be decreased ...