How to test a Tach

I would think that you would have to have a pulse generator of some sort.
You could always send it out. How about making a test rig with a running car. You would have to be careful that you don't shock the piss out of yourself. I would opt for the sending it out.

Paul

I was checking the wiring diagram to see what color wires to hook up ( I am going to test it on another car) the three wires that hook to the rev counter (I am assuming this means tach) are labeled N, B, and what looks like, SS. what do those stand for, I am hoping colors and not simply negative, battery and signal. But it looks like N(+),B(signal),SS(-)???

You're right, the diagrams are labelled with colours - Nero, Bianco and ... I can't remember what S stands for but I think it's pink, from memory. That would be the switched 12V supply which comes on when the key is turned to "run". There's rosso (R, red), verde (V, green), giallo (G, yellow), marron (M, brown), azzurro (A, blue). The two letter codes indicate wire colour and stripe colour.

Sounds good, I will know more when I actually go to the garage where the car is.

S = rosa = pink.

I show three wires to the tach (rev counter)

B = white - signal from ignition coil negative terminal (#1)
N = black - ground
SB = pink with white stripe - switched hot