I seem to have a similar problem. I have a 83 300 SD and after I installed the Euro headlights all my dashboard light went out a while after. Trying to trace the fault it came to my attention that I didn't have any power going through the #12 fuse which handles the dashboard amongst other things. So far I haven't had any luck yet tracing the fault to it's source. Oh, I also detailed the interior deeply, which in this case means I took all the carpets and seats out. I really would appreciate any suggestions.