89 OMC 4.3 - I am trying to wire the tach. It has 4 wires. I know the red is positive and the black negative. The old tach had 1 grey wire going to it. The new tack has a green and white wire in addition to the red and black. Does the grey tach wire coming from the engine go to the green or white wire on the tach? What is the wire left over for?
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