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 troubleshootingSystem description
General
In conjunction with an impact absorbing structure for
a frontal collision, the srs (supplemental restraint
system) driver airbag, front passenger airbag and
driver side knee airbag were designed to
supplement seat belts in the event of a frontal
collision in order to help ...
Blower unit
Components
Removal
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove upper instrument panel
Remove the upper ...
Cooling fan system
Parts location
System diagram
On-vehicle inspection
Hint:
It is normal for the cooling fan to sometimes rotate when the
ignition switch is turned from acc to on.
Check cooling fan operation at low temperatures (below 94°c (201°f))
Turn the ignition switch on with the a/c ...