Marten, This is unfortunately one of the areas with the E31 where you need the electronic expert with proper experience and knowledge. This occurance could be related and it could also be a weird coincidence, unless it happens together every single time. Regardless, it takes the honest expert which is always hard to find. Your right in asking here though because some of the guys here do have this kind of knowledge and/or experience. Wiring is my achilles heel unfortunately. Good Luck Kurt