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 troubleshootingYaw rate and deceleration sensor
Components
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 front seat assembly lh
For manual seat: ...
Installation
Install water pump assembly
Remove any old seal packing material from the
contact surface.
Apply a continuous line of seal packing as shown in
the illustration.
Seal packing:
toyota genuine seal parking black, three
bond 1207b or equivalent
Standard seal diameter:
2.2 To 2. ...
PCS (Pre-Collision System)
The pre-collision system
uses a radar sensor and
front camera to detect
objects in front of
the vehicle. When the system
determines that the
possibility of a frontal collision
with an object is high,
a warning operates to urge
the driver to take evasive
action and the potential
brake pressure is inc ...