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 troubleshootingEngine compartment
Engine coolant reservoir
Engine oil filler cap
Battery
Brake fluid reservoir
Fuse box
Radiator
Condenser
Electric cooling fans
Engine oil level dipstick
Washer fluid tank
Engine oil
With the engine at operating temperature and turned off, check the oil
level on the dips ...
On-vehicle inspection
Inspect refrigerant pressure with
manifold gauge set
This method uses a manifold gauge set to locate
problem areas. Read the manifold gauge pressure
when these conditions are established. Test
conditions:
Temperature at the air inlet is 30 to 35°c (86 to
95°f).
Engine is ...
Before refueling the vehicle
Close all the doors and windows, and turn the engine switch to the
“lock” position (vehicles without a smart key system) or off (vehicles
with a smart key system).
Confirm the type of fuel.
Fuel types
Unleaded gasoline (octane rating 87 [research octane number 91] or
higher)
Cauti ...