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 troubleshootingInstallation
Caution:
Be sure to read the precautionary notices concerning the
srs airbag system before servicing it (see page rs-1).
Install steering pad assembly
Support the steering pad with one hand as shown in
the illustration.
Connect the 2 airbag connectors.
Notice:
When handling t ...
Only passenger door lock / unlock functions do not operate
Description
The main body ecu receives lock / unlock switch signals and activates the
door lock motor accordingly.
Wiring diagram
Inspection procedure
Read value of intelligent tester (lock position switch)
Use the data list to check if the door lock is
functioning properly.
...
Air mix damper control servo motor circuit (driver
side)
Description
The air mix damper servo 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 mix damper (driver seat) to the appropriate position. T ...