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 troubleshootingFootwell light
On-vehicle inspection
Inspect footwell light
Connect the battery's positive (+) lead to terminal 2
and the negative (-) lead to terminal 1, then check
that the light comes on.
Ok:
light comes on.
If the result is not as specified, replace the light. ...
Thermostat
Components
Removal
Remove no. 1 Engine under cover
Drain engine coolant (see page co-6)
Remove radiator support opening cover
Disconnect no. 2 Radiator hose
Remove water inlet
Remove the 2 nuts and disconnect the water inlet
from the cylinder block.
Remove thermostat
...
Air inlet damper control servo motor circuit
Description
The damper servo (air inlet control) sends pulse signals to indicate the
damper position to the air
conditioning amplifier. The air conditioning amplifier activates the motor
(normal or reverse) based on
these signals to move the air inlet control damper to the appropriate pos ...