service light flashes

[hagenfam4]

Just bought a 93 BMW 318is for my son. Its the first time working on a BMW. The problem is when you start and drive at slow speeds everythings fine, but at faster speeds the engine service light flashes, also does the clock lights and low beam headlights flashes. I don"t think it any codes becauce of the random of the flashing. I thinking its a grounding problem like a lose wire. Is this a common problem? What and where should I start at?