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 troubleshootingIf the vehicle battery
is discharged
The following procedures may be used to start the engine if the
vehicle’s battery is discharged.
You can also call your toyota dealer or a qualified repair shop.
If you have a set of jumper (or booster) cables and a second vehicle
with a 12-volt battery, you can jump start your vehicle by fo ...
Removal
Hint:
Use the same procedures for the rh side and lh side.
The procedures listed below are for the lh side.
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 ...
Skid control buzzer circuit
Description
The skid control buzzer sounds while the vsc is activated.
Wiring diagram
Inspection procedure
Notice:
When replacing the abs and traction actuator, perform the zero point
calibration (see page bc-
24).
Check can communication system
Check if the can communication d ...