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 troubleshootingData list / active test
Read data list
Hint:
Using the intelligent tester's data list allows switch,
sensor, actuator, and other item values to be read
without removing any parts. Reading the data list
early in troubleshooting is one way to save time.
Notice:
In the table below, the values listed under "no ...
Stop light switch circuit
Description
While driving with the cruise control, if the ecm detects that the brake
pedal is depressed, the cruise
control operation will be canceled. The stop light switch sends brake pedal
status signals to the ecm.
When the brake pedal is not depressed, terminal st1- is equal to the ...
On-vehicle inspection
Check camshaft timing oil control valve
assembly
Check the operation.
Connect the intelligent tester to the dlc3.
Turn the ignition switch on.
Turn the intelligent tester main switch on.
Start and warm up the engine.
Select the menu items: diagnosis /
enhanced obd ii / ...