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 troubleshootingShort in motor circuit
Description
The power steering ecu supplies current to the power steering motor through
this circuit.
Inspection procedure
Reconfirm dtc
Check for dtc.
Ok:
dtc is not output.
Replace power steering ecu ...
Disassembly
Remove magnetic switch assembly
Remove the nut and disconnect the lead wire from
the magnetic switch.
Remove the 2 screws holding the magnetic switch
to the starter drive housing.
Remove the magnetic switch.
Remove the return spring and plunger from the
starter drive hou ...
Instrument panel
Engine switch
Starting the engine/changing the modes
Emergency stop of the engine
When the engine will not start
Warning messages*1
Shift lever
Changing the shift position
Precautions against towing
When the shift lever does not move
Meters
Reading the meters/adjusting the instrument pa ...