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 troubleshootingIf your vehicle overheats
The following may indicate
that your vehicle is overheating.
The engine coolant temperature
gauge shows the red zone or a
loss of engine power is
experienced. (For example,
the vehicle speed does not
increase.)
"Engine Coolant Temp High
Stop in a Safe Place See
Owner's Manual" is shown
on ...
Terminals of ecu (2006/01- )
Check air conditioning amplifier
Measure the voltage and resistance of the
connectors.
Hint:
Check from the rear of the connector while it is
connected to the air conditioning amplifier.
Hint:
*: For 2gr-fe
Using an oscilloscope, check waveform 1.
Can communi ...
How to proceed with troubleshooting
Hint:
Use these procedures to troubleshoot the key reminder
warning system.
*: Use the intelligent tester.
Vehicle brought to workshop
Inspect battery voltage
Standard voltage:
11 to 14 v
Hint:
If the voltage is below 11 v, recharge or replace the battery
before proceedi ...