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 (2005/11-2006/01)
Install sliding roof weatherstrip
Install the sliding roof weatherstrip.
Position the joint of the weatherstrip at the rear
center.
Align the marks on the weatherstrip with the
middle marks at the corners of the plastic on
the edge of the sliding roof panel and install the ...
Compressor and pulley (for 2gr-fe)
Components
Removal
Discharge refrigerant from
refrigeration system (see page ac-172)
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 pretensione ...
Unlock warning switch
Inspection
Inspect unlock warning switch assembly
Measure the resistance of the switch.
Standard resistance
If the result is not as specified, replace the switch
assembly.
Ecu power source circuit
Description
This circuit provides power to operate the transponder key ecu.
Wir ...