Recently, some gauges stopped working on my 1990 300E. The tach, water temp, gas, and oil pressure gauges suddenly quit, although the car still runs fine. Coincidence or not, a buzzing noise started coming from one of the relays near the fuse box at the same time. The relay (M-B part No. 201-821-00-47) is supposed to be for the lighting. The lights operate as they should. Does anyone have an idea what could have caused my gauges to suddenly stop working? It was a pretty hot day in Central Texas, I had just stopped to put gas, and the temp was running just above 100C. Thanks for any input or ideas...