What does it mean when the tachometer needle goes to zero?
What does it mean when the tachometer needle goes to zero? If the needle goes to zero this indicates the tach is working and 12 volts and ground are present. If the needle does not move,either the circuit board is bad or 12 volts or ground are missing to the tach. What should I do if my tachometer is not working? TAKE THE CABLE LOOSE FROM THE TRANSMISSION AND CHUCK IT UP TO THE REVERSIBLE DRILL AND HAVE A FRIEND SIT IN THE CAR. POWER UP THE DRILL AND IF THE SPEEDOMETER JUMPS AROUND AND IS UNSTABLE, THE PROBLEM COULD...