Jetta GL Wagon L4-1.9L DSL Turbo (ALH) (2002)
Alarm Module: Initial Inspection and Diagnostic Overview
Golf, GTI and Jetta from m.y. 2002 are equipped with Immobilizer Generation III.
Generation III has the same functionality as the previous version. However, in addition to the normal data exchange between the immobilizer control
module and ignition key, Gen. III includes data exchange between the immobilizer control module and Engine Control Module (ECM).
Data exchange between the Immobilizer control module and ECM takes place over the vehicle CAN-Bus network.
NOTE: Ignition keys for Immobilizer III may be marked "W3".
Immobilizer functions supported by:
control electronics integrated with instrument cluster
a warning light for anti-theft immobilizer -K117- in instrument cluster (speedometer display)
an adapted engine control module
an induction coil on the ignition lock
Adapted ignition keys with electronic components (transponder and response reader memory)
Immobilizer III uses encrypted codes to increase anti-theft protection.
With encrypted codes, the control module for anti-theft immobilizer randomly generates a number and transmits it to the encryption transponder in the
Each transponder contains its own fixed code. The transponder uses a specific algorithm to calculate a new number based on the transmitted number and
the fixed code.
This new number, the "encrypted code" is sent back to the control module for anti-theft immobilizer where it is backtracked according to the same
The backtracked number and the original, randomly generated number must match. The key is then recognized as authorized.
Following recognition of the authorized key, a variable code is transmitted to the Engine Control Module (ECM).
The variable code is randomly re-generated in the Engine Control Module (ECM) after each engine start and is stored in both control modules.
If the variable code in the control module for anti-theft immobilizer and in the Engine Control Module (ECM) match, the engine can be started/ vehicle
For troubleshooting, initiate On Board Diagnostic (OBD) program and read out stored data using Scan Tool VAG 1551/1552 or VAS 5051 Vehicle
Diagnostic Testing and Information System. See: Scan Tool Testing and Procedures/Scan Tool Testing/Scan Tool Connecting and Initial
Checks/Initiating & Checking Control Module Versions
Malfunction Recognition and DTC Display
Malfunction Recognition And Diagnostic Trouble Code (DTC) Display Via Warning Light For Anti-theft Immobilizer
An intact immobilizer system is indicated by the warning light for anti-theft immobilizer -K117- lighting up and going out after approx. 3 seconds when
the ignition is switched on.
When the ignition is switched "on", the warning lamp flashes or lights up continuously to indicate a malfunction in the system when:
Adapting the ignition key has been carried out incorrectly
No transponder (response reader memory) is present in ignition key.
An unauthorized ignition key is used.
An unauthorized engine control module is detected.
A malfunction in the induction coil of anti-theft immobilizer -D2-.
A malfunction in the data wiring is present.
The warning light for anti-theft immobilizer -K117- does not light up after switching on ignition: