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 troubleshootingSource voltage drop
Description
The srs is equipped with a voltage-increase circuit (dc-dc converter) in the
center airbag sensor in
case the source voltage drops.
When the source voltage drops, the voltage-increase circuit (dc-dc converter)
functions to increase the
voltage of the srs to a normal working lev ...
Installation
Install air conditioner unit assembly
Install the a/c unit with the bolt and nut.
Torque: 9.8 N*m (100 kgf*cm, 7 ft.*Lbf)
Install instrument panel reinforcement
Install the instrument panel reinforcement with the 6
bolts.
Torque: 20 n*m (204 kgf*cm, 15 ft.*Lbf)
...
Removal
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove radiator support opening cover
Remove front wheel rh
Remove no. 1 ...