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 troubleshootingCommunication malfunction no. 1
Description
This dtc is output when a communication error occurs between the transponder
key amplifier and
transponder key ecu. Some possible reasons for the communication error are: 1) 2
or more ignition keys
are positioned too close together, or 2) noise is occurring in the communicatio ...
If your vehicle has to be stopped in an emergency
Only in an emergency, such
as if it becomes impossible
to stop the vehicle in the
normal way, stop the vehicle
using the following procedure:
Stopping the vehicle
1. Steadily step on the brake
pedal with both feet and
firmly depress it.
Do not pump the brake pedal
repeatedly as this will increase t ...
Problem symptoms table
Hint:
Use the table below to help determine the cause of the
problem symptom. The potential causes of the symptoms
are listed in order of probability in the "suspected area"
column of the table. Check each symptom by checking the
suspected areas in the order they are listed. Re ...