Wiring digital tach. to a f70

[Mark r Lindstrom]

Just bought a new 8350 round tach for my 2012 f 70 with a tiller handle. Also bought the overpriced Yamaha harness and the 2 fuse rats nest thingy dingy. The one 4 pin cable is simple enough, but where do I hook up the other four wires (black, green, yellow and blue) coming out of the tach, and what do they each do?
Been looking and reading online....finding little or no help.
I want the tach on only when the motor is on.
Thanks,
Mark