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 troubleshootingCompressor circuit
Description
When the a/c switch is turned on, the magnetic clutch on signal is sent from
the air conditioning
amplifier. Then the mg clt relay turns on to operate the magnetic clutch.
Wiring diagram
Inspection procedure
Inspection procedure
Perform active test by intelligent tester (a ...
Terminals of ecm
Hint:
The standard normal voltage between each pair of ecm
terminals is shown in the table below. The appropriate
conditions for checking each pair of terminals are also
indicated. The result of checks should be compared with the
standard normal voltage for that pair of terminals, displayed ...
Brake warning light does not come on
Wiring diagram
Refer to the brake warning light circuit (see page bc-145).
Inspection procedure
Check can communication system
Check if the can communication system dtc is output
(see page ca-34).
Result
Perform active test by intelligent tester (brake warning light)
...