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 troubleshootingCenter airbag sensor assembly communication circuit malfunction
Description
The center airbag sensor communication circuit consists of the occupant
classification ecu and the
center airbag sensor.
Dtc b1790 is recorded when a malfunction is detected in the center airbag sensor
communication circuit.
Wiring diagram
Inspection procedure
Hin ...
If 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.
Restarting the engine
If you have a set of jumper (or
booster) cables and a second
vehicle with a 12-volt battery,
you can jump start you ...
Short in driver side squib circuit
Description
The driver side squib circuit consists of the center airbag sensor, the
spiral cable and the steering pad.
The circuit instructs the srs to deploy when the deployment conditions are met.
These dtcs are recorded when a malfunction is detected in the driver side squib
circui ...