72 Skylark 350 coupe......Finishing up odds and ends before selling, part of which refurbishing wires.....the factory tach has: RED BLACK GREEN BLUE wires coming out the back, previous owner used WIRE NUTS to splice into harness! Any way, starting over since tach wasn't working, so if someone out there knows which wire goes where, I'd sure appreciate it!
That isn't a factory tachometer. The factory tach has only one signal connection. Most aftermarket tachometers have 3 or 4 wires. Red is 12 volts switched power (ignition on) Black is chassis ground The other 2 wires are the signal wire (probably Green), and possibly the lighting (Blue?) I suggest you take a closer look at the blue and green wires. See if one of them is for the lighting.
