Engine immobilizer system


The engine immobiliser system is a theft deterrent system for vehicles. This system prohibits the engine from starting by igniting the engine and injecting fuel when any keys other than the ignition key with a ID code* previously registered in the vehicle is used.
While the engine immobiliser system is set, the security indicator light flashes to indicate that the system is set.
The engine immobiliser system consists of the transponder chip, transponder key coil, transponder key amplifier, transponder key ECU, engine ECU, etc.
There are two types of engine immobiliser systems, one that controls by a separate ECU (transponder key ECU), and another that controls by an ECU (engine ECU) that is integrated with the transponder key ECU.
*ID code (transponder key code)

1.Engine immobiliser set/unset function
(1)Engine immobiliser set
The moment the ignition key is pulled out of the key cylinder or 20 seconds after the key is turned to ACC or LOCK position, the engine immobiliser is set and ignition of the engine and injection of fuel is disabled.
With the engine immobiliser set, even if the ignition switch that is removed from the ignition key cylinder is turned directly using a flat-head screwdriver or equivalent to START position in order to start the starter, the engine cannot be started. This is because the engine is not ignited and fuel is not injected.
(2)Engine immobiliser unset

2.Transponder key code registration function
The transponder key code registration function consists of an initial (automatic) registration, additional registration, and deletion.
The master key registered in the ECU is used to perform additional registration and deletion.
Refer to the Repair Manual (North America) or Service Bulletin (General country) for details.
(1)Initial registration of key code
This is a system to automatically register a new transponder key code (master key code and sub-key code) when the ECU is replaced.
After the ECU is replaced, turning the ignition switch ON makes the security indicator lamp blink. In this condition, inserting the master key and sub-key in the ignition key cylinder automatically registers the transponder key code in the ECU.
In the initial (automatic) registration mode, the transponder key code can be registered for up to three or four keys. The last registration (the third or fourth key) is performed at the sub-key registration mode.
After the initial registration, it may take some models approximately 30 minutes to match the communication ID between the transponder key ECU and the engine ECU.
(2)Registration of additional key code
This is a function to perform the additional registration of a new transponder key code (master key code and sub-key code) with the transponder key code registered in the ECU.
The figure shows an example of the additional registration method for the transponder key ECU control type. This registration method is performed by ignition switch operation and the open/close operation of the driver’s door.
Additional registration can also be performed using a hand-held tester.
For the engine ECU control type, registration and erasure are performed by operating the brake pedal and accelerator pedal.
The number of the registration of the transponder key code varies depending on the models.
(3)Erasure of key code
This is a function to erase all the transponder key codes except for the master key code that is used for the erasure.
(4)The difference between master key and sub-key
Two or three master keys and a sub-key are set in the ignition keys for the engine immobiliser system. Registration and erasure of the key can be performed only by the master key. Therefore, to register the sub-key, the master key is necessary. The setting of the master key and sub-key is also classified according to the registration methods.
(5)When all the master keys are lost
If all the registered master keys are lost, to register a new key, replacement of the transponder key ECU or Engine ECU and a set of keys is required.
In some countries, some models have a key code reset function.

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