Had problem with intermittent dash indicator lights not working at key-on position. Only shift arrow would lite and alternator circuit would not charge resulting in battery run down and engine died. Tapping on dash would sometimes restore function. Worse when dash was warm/hot ie in sun for a while. Ignition switch replacement did not solve problem. Replaced flexible circuit board on back of instrument cluster and problem seems to have been solved. BUT now speedo will sometimes register 30-40 mph when key is on, not running. Seems to cycle with something in maybe the ECM and will settle down. Once driving the speedo will begin to register and all is ok. Double checked all connections on instrument cluster and positive speedo/ power connection is good. What else could have started problem or are the two problems related? Is it possible the new circuit board is bad?

 

sorry, car is a 91 940 SE