Originally Posted by Taran.J
I believe d2s run a 55w ballast not 35w h7's use. I ran into this problem with my 2000 a4 when I did a swap it wouldn't power on, try a 55w ballast set and give it a test using your existing wiring set up and plug in the headlights to the BMW. This should fix the problem and not give you errors or the physical headlight out problem.
Thank you! I will definitely give it a try and see what happens. I hope 55w ballast works.