My 1988 560SL had this same issue once before, but it went away within a day. Basically, the speedo, tach and rest of the instrument cluster, along with the power windows, brake lights and turn signals, are inop. I've checked all the fuses, which look fine, although I did not see a fuse for anything except power windows. I dropped by my friendly mechanic, who said it might be a relay. Is there one relay which controls all these items, and where is it located? Thanks for your help!