Mercury – Inner Helm Extension Harness | 50-Foot Extension | 84-8M0173574

Overview
This 50-foot inner-engine extension harness is meant for big triple- and quad-engine boats where the normal harness just doesn’t have the reach. When the run has to make its way through long rigging channels or around multiple bulkheads, this extension keeps you from stretching the wiring or bending it too sharply. It lets the harness follow a smooth, relaxed path so the controls feel steady. On large offshore rigs, having this much extra room makes rigging and future service a lot easier.

Key Features
    • 50-Foot Extension – Built for long inner-engine routing paths.
    • Inner-Engine Use – For inner engines on triple and quad DTS layouts.
    • OEM Connectors – Factory ends that seat firmly and hold tight.
    • Flexible Routing – Helps avoid sharp bends, pinch points, and rubbing spots.
    • Stable Signal Path – Keeps throttle and shift communication clean.

Engine & Boat Compatibility
    • Triple engine
    • Quad engine
    • Inner-engine helm pathways

Performance & Practical Benefits
With this extension in place, the harness can follow a natural route instead of squeezing through tight areas. Controls usually feel smoother because nothing is kinked or under tension. It also gives you more space in the rigging bay so routine checks and repairs aren’t a fight. On wide-beam boats, that breathing room makes the whole system feel calmer and more predictable.

Why Buy OEM
OEM harnesses hold up to vibration, heat, and saltwater better than generic wiring. The connectors match Mercury’s DTS system exactly, which helps prevent loose plugs, glitches, or intermittent signals. It’s wiring you can count on when conditions get rough.

FAQ
Q1: How do I know I need the 50-foot version?
A: If the inner-engine run is still tight with shorter lengths, this is the version that usually reaches cleanly.

Q2: Any setup or calibration needed?
A: No—just plug it in and route it.

Q3: Saltwater friendly?
A: Yes. Rinse occasionally and check the connectors like usual.

Q4: Any installation tips?
A: Use wide, smooth curves and avoid areas where the harness might rub.

Q5: What are early signs of wear?
A: Sluggish controls, momentary signal drops, or jacket abrasion along tight spots.