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 troubleshootingBack door
The back door can be locked/unlocked and opened/closed by
the following procedures.
Locking and unlocking the back door
Door lock switch
Entry function (if equipped)
Wireless remote control
Opening/closing the back door from inside the vehicle (vehicles
with a power back door)
Press a ...
Cooling fan system
Parts location
System diagram
On-vehicle inspection
Hint:
It is normal for the cooling fan to sometimes rotate when the
ignition switch is turned from acc to on.
Check cooling fan operation at low temperatures (below 94°c (201°f))
Turn the ignition switch on with the a/c ...
If you think something is
wrong
If you notice any of the following
symptoms, your
vehicle probably needs
adjustment or repair. Contact
your Toyota dealer as
soon as possible.
Visible symptoms
Fluid leaks under the vehicle
(Water dripping from the air
conditioning after use is normal.)
Flat-looking tires or uneven
tire wear
...