Tac not working

[YAN-3]

I have a buddy who owns a 320i. his tac stoped working and he swaped out the old one with a newer unit. still nothing any clue as to what i can be?

[Court M3]

ground nut on back? SI board batteries getting weak? Any other symptoms? check your PM

[Gus]

check the PCB, i had the same problem recently and found a burnt out wire on the circuit board...changed the board and away laughing. i dont mean the SI board, i mean the board that the tacho/speedo mounts on to