Volkswagen Workshop Service and Repair Manuals

Valid for Golf Convertible ▸ 12.97, Golf, Golf Estate and Vento

For the Golf Convertible ▸ 12.97, Golf, Golf Estate and Vento the first generation immobilizer has been installed.

Notes:

• ◆ Self-diagnosis of the immobilizer can only be performed using the Vehicle Testing, Measuring and Information System VAS 5051.
• ◆ Observe additional information and prerequisites when working with 7-digit PIN=>page 01-9 .

Communication of the immobilizer control unit and engine control unit is performed via the W line.

The electronic immobilizer consists of:

• ◆ an immobilizer control unit
• ◆ an adapted engine control unit
• ◆ a reader coil on the ignition lock
• ◆ adapted ignition keys with electronic components (transponder and response reader memory)

Valid for Golf Convertible 01.98 ▸ 04.99

From 01.98 to 04.99 the 2nd generation immobilizer has been installed in the Golf Convertible.

Notes:

• ◆ Self-diagnosis of the immobilizer can only be performed using the Vehicle Testing, Measuring and Information System VAS 5051.
• ◆ Observe additional information and prerequisites when working with 7-digit PIN=>page 01-9 .

Communication of the immobilizer control unit and engine control unit is performed via the W line.

The electronic immobilizer consists of:

• ◆ an immobilizer control unit
• ◆ an adapted engine control unit
• ◆ a reader coil on the ignition lock
• ◆ adapted ignition keys with electronic components (transponder and response reader memory)

Valid for Golf Convertible 05.99 ▸

From 05.99 the third generation immobilizer is installed in the Golf Convertible.

Notes:

• ◆ Self-diagnosis of the immobilizer can only be performed using the Vehicle Testing, Measuring and Information System VAS 5051.
• ◆ Observe additional information and prerequisites when working with 7-digit PIN=>page 01-9 .

Communication of the immobilizer control unit and engine control unit is performed via the W line.

The electronic immobilizer consists of:

• ◆ an immobilizer control unit
• ◆ an adapted engine control unit
• ◆ a reader coil on the ignition lock
• ◆ adapted ignition keys with electronic components (transponder and response reader memory)

Function for all vehicles

With the 2nd generation of immobilizer the so-called "Cryptocode" principle has been introduced to improve the anti-theft security.

This "Cryptocode" principle selects a number at random in the immobilizer control unit and transmits it to the "Crypto" transponder in the ignition key.

Each transponder has its own "fixed code". After a predetermined procedure the transponder calculates a new number from the number which was transmitted and the "fixed code".

This new number, the "Cryptocode" is transmitted back to the immobilizer control unit where it is calculated back using the same predetermined procedure.

The result of the back calculation and the initial number selected at random must tally. The key will then be recognised as an authorised key.

After the key has been recognised as being authorized a "variable code" will be transmitted to the engine control unit.

The "variable code" will be randomly selected in the engine control unit after each time the engine is started and stored in both control units.

If the "variable code" in the immobilizer and engine control units tally, the vehicle can be put into operation.

To fault find, initiate self-diagnosis and interrogate the stored information with the Vehicle Testing and Information System VAS 5051.