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 troubleshootingInspection
Inspect water pump assembly
Visually check the drain hole for coolant leakage.
If leakage is found, replace the water pump
assembly.
Turn the pulley, and then check that the water pump
bearing moves smoothly without making a "click"
noise.
If it does not move s ...
Diagnosis system
Description
Data of the system can be read through the data
link connector 3 (dlc3) of the vehicle.
Therefore, when the system seems to be
malfunctioning, use the intelligent tester to check for
a malfunction and repair it.
Check dlc3
The vehicle's ecm uses iso 157 ...
Tc and cg terminal circuit
Description
Connecting terminals tc and cg of the dlc3 causes the skid control ecu to
display 2-digit dtcs by
flashing the abs warning light.
Wiring diagram
Inspection procedure
Check dlc3 (tc voltage)
Turn the ignition switch on.
Measure the voltage of the dlc3.
Standar ...