Sierra Boat-Side Wiring Harness 18-99447 for Johnson/Evinrude Outboard Control Box, Round Plug, 20 Feet

The Sierra 18-99447 is a boat-side wiring harness that connects a Johnson/Evinrude outboard engine to its remote control box. It uses a round plug connector on the boat side and terminates in a red plug, making it straightforward to identify and connect during installation. The harness runs 20 feet long, giving installers enough length to route wiring from the transom-mounted engine connection point forward to the helm or console-mounted control box without needing to splice in extension wiring.

Constructed with a polycarbonate (PC) housing at the connector, the harness is built to withstand the vibration, moisture, and temperature swings typical of a marine engine compartment and helm run. Because this harness is dedicated to Johnson/Evinrude outboard electrical systems, it is intended as a direct replacement or upgrade for the boat-side portion of the engine-to-control wiring, restoring a clean, secure connection between the outboard and the control box.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-99447
• Application: Johnson/Evinrude Outboard Boat-Side Wiring Harness
• Connector Type: Round Plug
• Plug Color: Red
• Length: 20 feet
• Material: Polycarbonate (PC)
• Weight: 2.3 pounds
• UPC: 808282396312

Fitment

Designed for Johnson/Evinrude outboard engine electrical systems, connecting the engine to the remote control box.

Replaces (OEM)

No OEM cross-reference numbers are listed for this part.

Frequently Asked Questions

What does the Sierra 18-99447 wiring harness connect? The Sierra 18-99447 is a boat-side wiring harness that connects a Johnson/Evinrude outboard engine to its remote control box.

How long is the 18-99447 harness? It measures 20 feet long, which is enough to route from a transom-mounted Johnson/Evinrude outboard connection point to a console or helm-mounted control box.

What type of connector does this harness use? The 18-99447 uses a round plug connector on the boat side, terminating in a red plug for easy identification during installation.

What is the plug on the Sierra 18-99447 made of? The plug housing is made of polycarbonate (PC), chosen for durability in a marine engine compartment environment.

Is the Sierra 18-99447 compatible with all outboard brands? No, the 18-99447 harness is built for Johnson/Evinrude outboard electrical systems and is not designated for other outboard brands.

How much does the 18-99447 harness weigh? The Sierra 18-99447 boat-side wiring harness weighs 2.3 pounds.

Does the 18-99447 come with any OEM cross-reference numbers? No OEM cross-reference or replacement part numbers are listed for the Sierra 18-99447 harness.

What color is the plug on this harness? The boat-side plug on the Sierra 18-99447 is red.

Can the 18-99447 be used to replace a damaged boat-side harness? Yes, the Sierra 18-99447 is intended as the boat-side wiring harness connecting a Johnson/Evinrude outboard to its control box, making it suitable for replacing a worn or damaged harness in that role.

Is the 18-99447 harness pre-terminated with connectors? Yes, the Sierra 18-99447 ships with a round plug connector already installed on the boat side for direct connection to the control box.