On account of the different characteristics of lamps with filament bulbs and lamps with LEDs, the control unit – known as “Body Control Module” (BCM) at VW – has to be “encoded”. Parameters are changed in the control unit in such a way that the LED rear combination lamps work perfectly. If this does not happen, fault messages will appear on the display and lamps will only have limited functionality. (The stop light in the tailgate can shine more brightly than the stop light in the exterior lamps).
Conversion is not possible with every BCM. There are different specifications for the Golf VI concerning the production date (vehicle) from which perfect functionality of the lighting functions is guaranteed. Before a vehicle is converted to LED lamps, we recommend reading out the BCM software version (see Figure 9).
Generally speaking, there are two different BCMs: The old one with software version 03XX. Proper conversion is not possible with this BCM. If a customer would still like to equip their vehicle with LED lamps, a new BCM will have to be installed as well. The old BCM cannot be updated to a newer software version.
Conversion is generally possible with the new BCM with the software version 05XX (0537, 0541). In vehicles with these software versions and standard xenon headlights, there is still a special factor that has to be taken into account: After the rear combination lamps have been encoded, the option “permanent driving light” (low beam is always activated when the engine is switched on) is no longer available. If this option is to remain active, the BCM must be updated to a newer version (SW version 0575 or later).