This happened to me as well, but only a few were illuminated. It turned out to be my alternator. Some type of short. A tow and repair total of $700 remedied the problem. This was the first of many problems I've had with my 96 850 that started right around 82K miles. I now have 126K and have had my rear main seal replaced, abs control module fail, heating fan fail, engine mounts wear out, sunroof leak, heat seaters die, various bulbs in dash won't illuminate, thermostat, etc. etc. etc.

Not saying all 850's are bad, but every problem they're know for, mine has had. Not to mention peeling door panels, weather strip aroudn windshield coming off and paint peeling off my roof rails.