General Information: Function

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 ignition key.

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 algorithm.

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 operated.

If malfunctions occur in the sensors and components being monitored, they will be stored in the Diagnostic Trouble Code (DTC) memory together with an indication of the type of malfunction. A maximum of 4 DTCs can be stored simultaneously.

Sporadic malfunctions are automatically cancelled if they are not repeated in next 50 engine starts.

For troubleshooting, initiate On Board Diagnostic (OBD) program using VAS 5051 Vehicle Diagnostic Testing and Information System and read out stored (DTC) data.