Mercury – Inner Helm Extension Harness | 40-Foot Extension | 84-8M0159763

Overview
This 40-foot inner-engine extension harness is built for wider or longer triple- and quad-engine boats where the standard harness won’t reach cleanly. When the wiring path has to run around bulkheads or span a long rigging channel, this length keeps you from pulling the harness tight or bending it into awkward corners. It lets the wiring take a smoother path, which helps the controls feel steady and predictable. On big offshore setups, that extra room makes rigging and service far easier.

Key Features
    • 40-Foot Extension – Extra reach for long inner-engine runs.
    • Inner-Engine Use – For the inner engines on triple and quad DTS layouts.
    • OEM Connectors – Factory ends that snap in securely.
    • Smooth Routing – Helps avoid pinch points and tight bends.
    • Reliable Signal Path – Keeps throttle and shift communication consistent.

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

Performance & Practical Benefits
With the extra length, the harness can take an easy route instead of weaving through tight gaps. That leads to smoother, more natural control response because the wiring isn’t being stressed. It also gives you more room to work during inspections or repairs, which makes a noticeable difference on big boats where space gets tight fast. Everything ends up looking cleaner and feeling more settled.

Why Buy OEM
OEM harnesses deal with vibration, heat, and saltwater far better than generic wiring. The connectors match Mercury’s system exactly, so you don’t end up chasing loose plugs or odd glitches. It’s dependable rigging that’s built to last.

FAQ
Q1: How do I know I need the 40-foot version?
A: If the inner-engine run still feels tight or won’t reach cleanly on a wide-beam or long-deck rig, this length usually fixes it.

Q2: Any setup needed?
A: Nope—just plug it in.

Q3: Saltwater use okay?
A: Yes. Rinse occasionally and check the connectors.

Q4: Any install tips?
A: Route it with wide, smooth curves and avoid rubbing points.

Q5: What are signs of wear?
A: Sluggish controls, intermittent signals, or visible jacket scuffing.