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 troubleshootingFuel pump
Components
Removal
Remove fuel tank assembly
Remove the fuel tank (see page fu-39).
Remove fuel tank main tube sub-assembly
Remove the joint clip and fuel tank main tube.
Caution:
Before removing the tube joint clip, check for
foreign matter around the cli ...
Terminals of ecu
Check power steering ecu
Hint:
Measurements cannot be performed on the c connector
side of the power steering ecu.
Measure the voltage and resistance of the
connectors.
If the result is not as specified, the ecu may have a
malfunction. ...
Check and replace ecu
Notice:
The connector should not be disconnected from
the ecu. Perform the inspection from the
backside of the connector on the wire harness
side.
When no measuring condition is specified,
perform the inspection with the engine stopped
and the ignition switch on.
Check that the con ...