Check wiring diagram to find out how illumination is managed: WDS BMW Wiring Diagram System - 3 E46
Dimming is managed by the Combi cluster. Indicator lights (high-beam, turn indication etc.) are sent via K-bus from lightning module to the combi cluster.
How the illumination is controlled, I didn't find out yet, but since the K-bus is connected to stereo, AC/Heater panel, lichtning module, combi cluster and more, I suspect the lightning module is malfunctioning.
Now there must be checked how the other matters are illuminated...