Vintage Tach

[Locus2298]

Hey guys, I bought this vintage Hawk Tach from an auction on EBay. It has a switch for 4-6-8 cylinder engines, depending the engine. I was able to determine that the Yellow is + for Tach light and the blue one is the negative for the Tach light, however, the black and green I don’t know. Any ideas?

 

[79 USA 1]

Found on another site for a Hawk Command tach with the following wire hook-up.
Green-coil, Yellow-tach light, Blue-ground for light, Black-ground for unit itself.

 

[scoti]

Hey guys, I bought this vintage Hawk Tach from an auction on EBay. It has a switch for 4-6-8 cylinder engines, depending the engine. I was able to determine that the Yellow is + for Tach light and the blue one is the negative for the Tach light, however, the black and green I don’t know. Any ideas?

Green is usually the tach signal from the distributor NEG term coil or HEI tach pin.
Black I would think is a chassis ground.

The other two I would bet.... One is for the 12v tach lighting so it illuminates w/the gauges. The other would be 12v power from the ignition circuit.