73 135 Johnson , What should AC voltage be on gray tach wire? Or what would HZ be? Tach only goes to 3 grand but idle rpm is ok . Tried another tach same thing. Is charging and rectifier test ok Tach is set to 12 poles . Any ideas?
What tachometer do you have? Were both tachometers you tried identical? Is there a dial on the back of the tachometers where one can set it #6, the #6 indicating "pulses"? Or, does the tachometer simply have terminals? Can you insert a picture of the back of the tachometers?
I've been in this line or work and have never looked into the actual AC or HZ readings.
Are those different places you can connect the signal wire too or are they aside of a selector switch? If it is a selector switch setting, switch it back and forth a few times to clean the internal contacts and make a better connection. They can get dirty some times.
