Key Learning
Inside every key there is a small chip called a “transponder”. In most cases this chip doesn’t
require an external power supply but is supplied from the magnetic field, which induces electric
current. The immobilizer recognizes whether a proper key is used to start a car exactly by using
the transponder. With the evolution of the VAG cars the transponder type and the records inside it
have changed. In general, there are five different types of immobilizers/transponders used. They
are called Immo I, Immo II, Immo III, Immo IV and Immo V. Systems from ImmoI till Immo III
require simply that a transponder from the proper type is found inside the key, and they are able to
learn these transponders.
Starting from Immo4 it is required that the transponder is from the proper type, but also has some
specific records inside it. Only transponders with such correct records can be learned. According
to the data inside there are the following types of transponders:
- Tp22 – dedicated for use inside Seat vehicles;
- Tp23 – dedicated for use inside Volkswagen vehicles;
- Tp24 – dedicated for use inside Skoda vehicles;
- Tp25 – dedicated for use inside Audi vehicles (especially A3 and A4);
Such transponders can be used in all cars of the specific producer (e.g. Tp24 can be used for all
Skoda models)
Abritus72 Ltd. can deliver modified transponders which are programmed with special data and
they have the abbreviations TA2, TA3, TA4 and TA5. Each of these TAx transponders can be
transformed with the Transponder programmer to the corresponding TP2x transponder which can be
then learned in the Immo IV systems, but also can be programmed with the Transponder programmer for
use in Immo V system, i.e. they can also be used for producing dealer keys.
Normally, there are several key-learning procedures which are applied depending on the car type
and year of production.
Normally, most of the newer cars require a transponder which is precoded with the VIN number
from a dealer. Fortunately, it is also possible to precode the transponder by yourself using the
Transponder programmer if you have available the 7 bytes of the component protection data and yo
need to use an TA2/TA3/TA4/TA5 transponder as base for this operation.
The 7 bytes of the component protection data are contained inside the immobilizer and sometimes
inside the engine control unit. Inside the engine control unit there are stored always at least 6 of
the component protection bytes, sometimes also the 7th byte is contained.
There are several ways to extract the component security:
- Simply press the “Autodetect component security” and the component security bytes will be
read from the ECU. This will also automatically decide whether you've the 7th byte, or you've to
search for it. Also the login will be displayed in the status bar. The autodetection is not alway
possible, it works basically for EDC16 and MED9x engines which are using CAN diagnostic
connection.
- The component protection bytes are displayed e.g. using the special function “Engine Control
Unit” - when reading the EEPROM of the engine control unit then VAG Commander will show
you the component security bytes:
If the 7th byte is different from “00” then you have all the 7 bytes of the component security and you
are able to prepare a transponder directly with the Transponder programmer. In this case you must
choose “All 7 bytes of the component protection data (component security are known)”, put the 7
bytes and press the “Program” button
If the 7th byte is not available you must choose “Find the 7th byte of the component protection
data” and you have to put the six bytes which are known. There are two possible ways to check
whether the 7th byte is matched:
- automaticaly
This mode requires that the immobilizer and the Transponder programmer can simultaneously read/write the
transponder. For this purpose it is necessary to put the programmer to the ring coil.
Autodetect CS bytes and login
Automaticly find the 7th byte
-Manually
The main difference between the automatical and manual procedure is that by the manual
procedure you should put the key into the programmer, then make a ignition with it, and then
once again to the programmer and so on until the byte is found.
If you use the manual procedure you will be consecutively invited to put the transponder into
the program, and than to give it to the ignition. Once again the channel and position of the
measured values should be put (as like in the automatical procedure).
Normally for the most models it is required that the key is in the ignition, and you change only
the position of the transponder. You will be invited to put the transponder into the programmer,
then to put it near ignition lock so it is read by the immobilizer. Exception from this is e.g. the
Passat B6. For it it is required that you put the key with the transponder is put into the
programmer, then the key with the transponder is put into the ignition lock, BUT TILL FIRST
POSITION, than again into the programmer, and again into the ignition lock until the byte is
found.
Manually find the 7th byte
Manually find the 7th byte
For vehicles with a Hitag2 Key (transponder) 2007+ or Audi A8 (CAN)
produced after year 2002 you need to prepare a Hitag2 key (transponder) before
you use the key learning function.
You can use a virgin transponder PCF7936 or a virgin key. There are following possibilities:
- Making the key without disassembling the Kessy (completely by OBDII).
The “Autodetect from ECU” button will try automatically to read the component security bytes
from the ECU, and will select for you automatically whether you need to search for the 7th byte
or not
- Making the key by disassembling the Kessy or the ECU
You can load a dump of the Kessy or ECU.
Prepare dealer key with Hitag2
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