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 troubleshootingComponents
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Data 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 in one way to save time.
Connect the intelligent tester (with can vim) to the
dlc3 ...
Automatic transaxle fluid
On-vehicle inspection
Check transaxle fluid level
Hint:
Drive the vehicle so that the engine and transaxle are at
normal operating temperature.
Fluid temperature:
70 to 80°c (158 to 176°f)
Park the vehicle on a level surface and set the
parking brake.
With the engine idling and ...