Mercury – MP Alert Harness Extension | 50-Foot Forward Routing Cable | 84-8M0054187

Overview

Some boats need the MP Alert warning lights positioned far forward—well beyond the reach of standard rigging lengths. The Mercury 84-8M0054187 MP Alert Harness Extension gives you 50 feet of cable, making it the longest forward-routing option available for MP Alert installations. With this harness, you can mount a Moving Prop Alert light near the bow or along extended deck areas so swimmers, guests, and riders see the warning long before they approach the stern.

Key Features

• 50-Foot Extension – Maximum-length harness for boats with long rigging runs or distant bow light locations.
• Plug-and-Play OEM Fit – Uses Mercury SmartCraft-grade connectors for a direct, reliable connection.
• Expanded Safety Visibility – Allows MP Alert lights to be mounted well forward for early swimmer awareness.
• Flexible Routing Capability – Long enough to pass through bulkheads, under decks, and along full-length rigging chases.
• Marine-Durable Construction – Sealed cable and connectors designed to handle spray, vibration, and harsh environments.

Compatibility

• All Mercury MP Alert systems using oval MP Alert lights
• SmartCraft-compatible engines
• MP Alert add-on lights, Y-harness expansion setups, and cowl-mounted options
• Boats requiring extended bow- or deck-mounted MP Alert lighting

Performance & Practical Benefits

This 50-foot harness lets you position a Moving Prop Alert light as far forward as needed—ideal for pontoons, long center consoles, cruisers, or boats with raised bow areas. The extra reach keeps the wiring tidy and prevents strain, while the MP Alert system itself continues to work automatically. Once connected, the added light flashes any time the prop is spinning, giving swimmers and riders a clear warning from more angles and greater distances.

Why Buy OEM

For safety systems like MP Alert, clean signal transfer and watertight connections matter. Mercury’s OEM harness matches the electrical requirements of the MP Alert controller and ensures the added light operates with the correct timing and brightness. Cheaper aftermarket extensions often loosen, corrode, or cause intermittent light behavior—but the factory harness is built and sealed for long-term marine reliability.

FAQ

Q1: When is the 50-foot extension necessary?
When you need to mount an MP Alert light far forward—common on large pontoons, long walkaround rigs, or boats with expansive upper decks.

Q2: Will this change how the MP Alert system works?
No. It only extends the wiring; the system still activates automatically when the prop moves.

Q3: Can this be used with Y-harness add-on kits?
Yes. It works seamlessly with all expansion components.

Q4: Is this compatible with cowl-mounted lights?
Yes. Any oval MP Alert light can use this extension.

Q5: Is installation difficult?
No. Plug it into the MP Alert harness and route it like any long cable run—secure with clamps or ties.