I have a 2000 D2 that I bought about a month and a half ago, and the entire time I've been plagued with strange headlights. I can't find any loose grounds or wiring issues, I've changed the bulbs, voltage seems good, but when I turn on my headlights, my dipped beams are tragically dim... kind of like daytime running lights. My brights work like a champ, naturally. Here's the kicker. When I turn on my lights, it doesn't matter. Turns out, my tragically dim headlights are coming on every time I shift out of park. I was under the impression that D2s didn't have daytime running lights, but apparently I not only have them, but they're linked to my transmission, not whether or not my car is running (Unlike any other car I've driven) and while they magically function, my dipped beams are functioning like daytime running lights.
I don't know a whole lot about electronics, I'm completely strapped for ideas on what's going on. What in the world did the previous owner do to my car?

 

IIRC, the DRL's functionality can be configured through the BCU by a dealer or service shop with the Testbook code reader. Obviously this isn't the only problem going on here, but it may be part of the answer you're looking for.

Also, are you sure the low beam filaments are actually coming on when you turn the lights on? How about the front side lights? (These are the little bulbs below the main bulb in the head light.)