IMMOBILIZER SYSTEM

The engine immobilizer system prevents the engine from starting and immobilizes the vehicle if a key other than the key registered for that vehicle is used in an attempt to start the engine after forced entry. The engine immobilizer system consists of the ignition key, key ring antenna, ETACS-ECU (immobilizer-ECU), and engine-ECU <M/T> or engine-A-M/T-ECU (engine automated manual transmission electronic control unit) <Automated manual transmission>. It works in the following way and has these functions.

With the ignition key turned ON, the transponder (a small transmitter) integrated in the ignition key transmits its own encrypted code to the key ring antenna via radio wave.
According to the sent encrypted code, the ETACS-ECU controls the engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission> only when the sent encrypted code agrees with the pre-registered one.

The system is designed to be maintenance-free because the power source for the transponder is supplied by the key ring antenna. Two ignition keys are provided, and up to eight keys can be registered to one vehicle as needed. More than one trillion of encrypted code combinations can be registered, and parts of them are irregularly changed whenever the ignition key is turned ON. This feature prevents code copying, resulting in higher security of the system.

note

In case of replacement of the ETACS-ECU, or loss or addition of the ignition key, all key encrypted codes must be registered again using M.U.T.-III as follows.

In case of loss of the ignition key, all keys except the lost one must be registered again for eliminating the registration of the lost key.
For addition of a key, all the keys to be used afterwards including the added key must be registered again.

DIAGNOSIS CODE TABLE

Diagnosis code No.	Diagnosis item
B1721	Base station failure
B1722	Antenna failure
B1723	Transponder communication failure
B1725	Wrong data/random number in CAN message
B1726	Too much challenges received
B1730	Key out of sync
B1731	Immobilizer communication failure

CONSTRUCTION DIAGRAM

MAIN COMPONENTS

Component name	Outline of function
Transponder	Is power-supplied by the key ring antenna. When the transponder receives random number data, it processes the encrypted code. Then it transmits the process result to the ETACS-ECU.
Key ring antenna (included an amplifier)	The ETACS-ECU supplies power via an antenna on a steering lock by transmission of electromagnetic waves to a transponder built into a key, using magnetic coupling
ETACS-ECU (immobilizer-ECU integration)	Supplies electrical power to the transponder integrated in the ignition key, and transmits random number data. Verifies the encrypted code which is sent from the transponder. If the code is correct, it sends an engine immobilization signal to the engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission>.
Engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission>	Starts the engine, and then continues the engine running if an engine mobilization signal is confirmed. If an engine immobilization signal is confirmed, the ECU cancels the engine control and stops the engine.

Encrypted code registration criteria table

The ignition key contains a transponder (small transmitter), which retains an unique encrypted code. Under any of the conditions below, the encrypted code must be registered in the ETACS-ECU again. The ETACS-ECU can retain maximum eight different encrypted codes. This means that maximum eight ignition keys can be registered.

Component to be replaced	Engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission>	ETACS-ECU	Ignition key
			*Master key^1 exist**	*Master key^1 does not exist**
When engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission> is replaced	The matching with ETACS-ECU is needed.	Must not be replaced	Must not be replaced
			Must not be registered again
When ETACS-ECU is replace	Must not be replaced	-	Must not be replaced	All ignition keys must be replaced
	The matching with ETACS-ECU is needed.		All ignition keys must be registered again^*2	All ignition keys must be registered^*3
When ignition key is added	Must not be replaced	Must not be replaced	Additional ignition key must be registered All ignition keys must be registered again
When ignition key is lost	Must not be replaced	Must not be replaced	All the ignition keys other than the lost one must be registered again to prevent them from being operated by stolen keys
	The matching with ETACS-ECU is not needed.

note

^*1: To check for master key and sub key, refer to Workshop Manual GROUP 54A, Ignition switch - On-vehicle service.
^*2: First, register the master key and then register the sub key.
^*3: The ignition key that has been registered first will be the master key.
When ETACS-ECU or engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission> is replaced, reinput the vehicle information with the variant coding, using the M.U.T.-III.