My electric tachometer is not reading correctly. What can I do?

Is this the correct tach for this application? Diesel tachs will not operate correctly on gasoline engines and visa versa.

Check the installation hook-up to make sure that wires are going to the correct studs. Make sure that the ignition and signal terminals are not grounded. There should be an insulating washer under the nut on these two terminals. The ground terminal should not have an insulating washer.

Wire unit according to installation instructions and remove the signal wire from stud. Turn on ignition key. The pointer should return to the zero position on the tachometer.

The installation sheets should match the tachometer model in the box. Calibration is impossible without correct charts for coding sequence.