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 troubleshootingCheck for open circuit
For an open circuit in the wire harness in fig. 1,
Check the resistance or voltage, as described below.
Check the resistance.
Disconnect connectors a and c, and measure
the resistance between them.
Standard resistance (fig. 2)
Hint:
Measure the resistance while lightly s ...
Air mix damper control servo motor circuit (driver
side)
Description
The air mix damper servo sends pulse signals to indicate the damper position
to the air conditioning
amplifier. The air conditioning amplifier activates the motor (normal or
reverse) based on these signals to
move the air mix damper (driver seat) to the appropriate position. T ...
Main body ecu communication stop mode
Description
Wiring diagram
Inspection procedure
Notice:
Turn the ignition switch off before measuring the resistances of the
main wire and the branch
wire.
After the ignition switch is turned off, check that the key reminder
warning system and light
reminder warning syste ...