Mercury – SmartTow Engine-to-Helm Harness | 20-Foot Connection Cable | 84-8M0101642

Overview

SmartTow and Cruise only work as well as the connection between the engine and the helm, and this harness is the link that makes the whole system communicate. The Mercury 84-8M0101642 Engine-to-Helm Harness provides the clean, reliable pathway needed for SmartTow functions on mechanical-control MerCruiser gas engines. Once installed, the helm kit and engine stay in sync, giving the driver smooth pull-ups, steady speeds, and a towing setup that feels modern and predictable.

Key Features

• SmartTow Communication Link – Connects the engine to the SmartTow/Cruise helm kit for full towing functionality.
• 20-Foot Length – Provides enough reach for most single-engine runabouts and tow-sport layouts.
• Mechanical Engine Compatibility – Designed specifically for mechanical-throttle MerCruiser gas engine platforms.
• Single-Engine Design – Engineered for one-engine towing setups only.
• Clean OEM Fit – Uses factory-style connectors for a reliable, plug-in installation.
• Stable Signal Transfer – Ensures smooth data flow between the engine control module and helm unit.

Engine & Boat Compatibility

• Marine-specific MerCruiser mechanical gas engines
• Single-engine tow-sport and runabout applications
• Systems equipped with SmartTow or Cruise helm kits

Performance & Practical Benefits

This harness delivers the stable communication SmartTow depends on. With a solid connection between the helm and the engine, pull-ups feel consistent, and speed control becomes easier for the driver to hold steady—even in turns or light chop. The 20-foot length offers enough flexibility for straightforward routing, and the factory connectors reduce troubleshooting and wiring guesswork. Once installed, the whole SmartTow system responds more predictably, making towing smoother for both the driver and the rider.

Why Buy OEM

SmartTow requires precise communication between the helm kit and the engine’s control module. Mercury’s OEM harness is built to match the exact pin layout, signal behavior, and shielding needed for clean data transfer. Aftermarket harnesses often introduce noise or poor connections, which can create inconsistent towing performance. The OEM version installs easily and maintains reliable communication season after season.

FAQ

Q1: How do I know if I need this harness?
If you’re adding SmartTow or Cruise to a mechanical-throttle MerCruiser gas engine, this harness is required for the helm kit to communicate with the engine.

Q2: Does the 20-foot length fit most boats?
Yes. It’s designed to reach cleanly from the transom area to the helm on typical single-engine layouts.

Q3: Will this harness affect normal throttle operation?
No. It only carries SmartTow and Cruise communication—your mechanical throttle feel remains unchanged.

Q4: Can this harness be used for twin engines?
No. It is built strictly for single-engine applications.

Q5: Does the harness need any programming after installation?
No additional programming is required. Once connected, the system communicates automatically.