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 troubleshootingTerminals of ecu
Skid control ecu
Hint:
*1: W/ 16-inch disc
*2: W/ downhill assist control
*3: For 2wd (w/ auto lsd)
Check skid control ecu
Disconnect the a19 ecu connector.
Measure the voltage and resistance of the wire
harness side connector.
Hint:
The voltage cannot be measured ...
Multiplex communication circuit
Description
The air conditioning amplifier communicates data with the ecm and combination
meter through the can
communication system.
Wiring diagram
Inspection procedure
Check dtc
Clear the dtc (see page ac-31).
Read the dtc (see page ac-31).
Result
Go to can c ...
For vehicles equipped with vehicle stability (vsc) system
Notices when using drum tester
Before beginning testing, disable the vsc. To
disable the vsc, turn the ignition switch off
and connect sst to terminals 12 (ts) and 4
(cg) of the dlc3.
Sst 09843-18040
Notice:
Confirm that the vsc warning light blinks.
Vsc system will be r ...