In Reply to: new clutch, now tachometer doesn't work posted by Eric on August 28, 2001 at 22:11:13:
if your engine works both these sensors are OK.
The first is TDC sensor and the second engine speed sensor. Both are used by Motronic. If either was kaput then the engine would not work.
The tach signal is the black wire in the harness on the motronic. On early M3s there is a plug (with 3 wires, but only one, the black, is actually used) next to the motronic above the glovebox.
I can't think how his could be damaged during clutch replacement. Maybe there is something else at fault. The tach itself? A fuse somewhere?