How can I tell if the correct voltages are getting to the back of the tach?
If you have a voltmeter, you can make the following measurements to help you troubleshoot: • On the DC 20V scale, put the red probe on the long stud, put the black probe on a good ground, meter should read 12V or higher. • On the DC 20V scale, put the red probe on the short stud, put the black probe on a good ground, meter should read 3V to 6V. (Note, since you are on the DC scale, you are reading the average DC voltage of the points. Since the points are opening and closing, the average is about 1/2 of the peak voltage. Also there is some voltage drop do to the ballast resistor, this is why you will read 3V to 6V).
