Mercury – Tachometer Harness | Engine Gauge Wiring | 84-86396A8Mercury Tachometer Harness Engine Gauge Wiring 84 86396A8 OverviewThis five pin tachometer harness gives you a clean, direct connection for systems using Mercurys Commander style controls. At four feet long, its sized well for most side mount layouts without leaving a bunch of excess wire to tame. On the water, it helps keep the tach reading steady instead of bouncing or cutting out. Its a simple, dependable piece meant for boats still running these