Mercury – Inner Helm Extension Harness | 15-Foot Extension | 84-8M0159758

Overview
This 15-foot inner-engine extension harness gives you the extra reach you often need on triple- and quad-engine boats. Sometimes the factory harness just won’t make the run cleanly—especially when the path dips around bulkheads or stretches across a wide rigging bay. This extension keeps you from forcing tight bends or stretching the wiring. It lets the harness settle into a smoother route so the controls feel normal and predictable.

Key Features
    • 15-Foot Extension – Adds useful slack for routing to inner engines.
    • Inner-Engine Use – Made for the inner engines on triple and quad DTS rigs.
    • OEM Connectors – Factory ends that snap in solidly.
    • Easy Routing – Helps avoid tight corners and pinched harness runs.
    • Steady Signal Path – Keeps throttle and shift response consistent.

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

Performance & Practical Benefits
A little extra length goes a long way on bigger boats. The controls usually feel smoother because the wiring isn’t kinked or squeezed into a corner. It also frees up space in the rigging area, which makes inspection and service work a lot less frustrating. Everything behind the scenes ends up looking cleaner and feeling more relaxed.

Why Buy OEM
OEM harnesses take vibration, heat, and saltwater in stride, and the connectors fit exactly the way Mercury designed. You avoid the random glitches and loose plugs that show up with generic wiring. It’s reliable, long-lasting rigging.

FAQ
Q1: How do I know I need this extension?
A: If your inner-engine harness feels tight or won’t reach cleanly, this 15-foot version usually solves it.

Q2: Do I need to program anything?
A: Nope—just plug it in.

Q3: Saltwater okay?
A: Yes. Rinse once in a while and check the connectors.

Q4: Any install tips?
A: Give it a gentle route with smooth bends so nothing gets stressed.

Q5: What are early signs of wear?
A: Hesitant controls, intermittent signals, or spots where the jacket is rubbing thin.