Mercury - Tachometer Harness Engine Gauge Wiring 84-86396A24. OverviewThis five-pin tachometer harness gives older Commander-series rigs a clean, reliable tach signal without rewiring the whole helm. At 13 feet long, it has the reach needed for side-mount controls on larger consoles or layouts where the run to the dash isn't short. On the water, it keeps the tach steady instead of cutting out or wandering when the boat hits chop. It's a straightforward, plug-in solution for boats still running t