The immobilizer system will disable the vehicle unless the
proper ignition key is used, in addition to the currently available
anti-theft systems such as car alarms, the immobilizer system aims to
drastically reduce the rate of auto theft.
1. |
Encrypted immobilizer unit
A. |
The immobilizer unit system consists of a passive challenge -
response (mutual authentication)transponder located in the ignition
key, an antenna coil, a encoded immobilizer unit, an indicator light and
the PCM(ECM). |
B. |
The immobilizer unit communicates to the PCM(ECM) (Engine
Control Module) via a dedicated communications line. Since the vehicle
engine management system is able to control engine mobilization, it is
the most suitable unit to control the immobilizer unit. |
C. |
When the key is inserted in the ignition and turned to the ON
position, the antenna coil sends power to the transponder in the
ignition key. The transponder then sends a coded signal back through the
immobilizer unit to the PCM(ECM). |
D. |
If the proper key has been used, the PCM(ECM) will energize
the fuel supply system. The immobilizer indicator light in the cluster
will simultaneously come on for more than five seconds, indicating that
the immobilizer unit has recognized the code sent by the transponder. |
E. |
If the wrong key has been used and the code was not received
or recognized by the PCM(ECM) the indicator light will continue blinking
for about five seconds until the ignition switch is turned OFF. |
F. |
If it is necessary to rewrite the PCM(ECM) to learn a new
key, the dealer needs the customer's vehicle, all its keys and the GDS
equipped with an immobilizer program card. Any key that is not learned
during rewriting will no longer start the engine. |
G. |
The immobilizer system can store up to eight key codes. |
H. |
If the customer has lost his key, and cannot start the engine, contact service station. |
|
2. |
Transponder / IMMO ECU / EMS authentication |
PCM (Power Train Control Module)
1. |
The PCM(ECM) (A) carries out a check of the ignition key
using a special encryption algorithm, which is programmed into the
transponder as well as the PCM(ECM) simultaneously. Only if the results
are equal, the engine can be started. The data of all transponders,
which are valid for the vehicle, are stored in the PCM(ECM).
ERN (Encrypted Randorm Number) value between EMS and
encrypted immobilizer unit is checked and the validity of coded key is
decided by EMS.
[G6DE - 3.0 gasoline] |
ENCRYPTED immobilizer unit (A)
The immobilizer unit carries out communication with the
built-in transponder in the ignition key. This wireless communication
runs on RF (Radio frequency of 125 kHz). The immobilizer unit is mounted
behind of the crash pad close to center cross bar.
The RF signal from the transponder, received by the antenna
coil, is converted into messages for serial communication by the
immobilizer unit device. And, the received messages from the PCM(ECM)
are converted into an RF signal, which is transmitted to the transponder
by the antenna.
The immobilizer unit does not carry out the validity check of
the transponder or the calculation of encryption algorithm. This device
is only an advanced interface, which converts the RF data flow of the
transponder into serial communication to the PCM(ECM) and vice versa.
TRANSPONDER (Built-in keys)
The transponder has an advanced encryption algorithm. During
the key teaching procedure, the transponder will be programmed with
vehicle specific data. The vehicle specific data are written into the
transponder memory. The write procedure is once only; therefore, the
contents of the transponder can never be modified or changed.
Antenna coil
The antenna coil (A) has the following functions.
- |
The antenna coil supplies energy to the transponder. |
- |
The antenna coil receives signal from the transponder. |
- |
The antenna coil sends transponder signal to the immobilizer unit.
It is located directly in front of the steering handle lock. |
Teaching Procedures
1.
Key Teaching Procedure
Key teaching must be done after replacing a defective PCM(ECM) or when providing additional keys to the vehicle owner.
The procedure starts with a ...
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