1986 yamaha 90 tach connection

tach has no wires connected to it. which wires do i need to connect to tach?
there are 2 greens with eylet and 2 blacks with eyelet taped up under console could this be them and are there any others to connect? THERE IS A PLACE FOR GRND, IGN, AND ONE MORE ON BACK OF TACH??

[boats.net]

There should be a yellow, green and black coming from key switch. Connect green to tach signal or sender post, yellow to ign and black to ground. Set tach for 12 pole.