Factory tach stopped working
Just picked up a 1964 409 biscayne! It has the factory tach in it that worked when I test drove it and the first time I took it out after coming home it worked. Now it has completely stopped working. My question is is there anyway to test it? When I shut the car off the need moves but otherwise it doesn’t register anything. I followed the three wires. The two that go to the fuse panel are attached and fuses are good and The other goes to the negative side of the ignition coil and seems just fine. Any ideas?