Sierra Johnson/Evinrude Engine Wiring Adapter Harness 18-99402, Adapts 1996-2016 Engines to 1976-1995 Controls

The Sierra 18-99402 is a wiring adapter harness built to bridge the electrical connection between newer Johnson and Evinrude outboard engines and older control systems. It allows an owner running a 1996-2016 Johnson or Evinrude engine to connect that engine to controls built for the 1976-1995 era, avoiding a full rewire or control-box replacement when upgrading or swapping a powerhead. The harness is designed for use in a marine environment, with connectors and wiring sized to handle the vibration, moisture, and temperature swings typical of an outboard engine compartment.

At 18 inches long, the harness is sized to route between the engine's wiring loom and the boat's existing control harness without excess slack. Because engine and control wiring configurations vary by model and production year, Sierra recommends checking the specific part numbers recommended for your engine and control setup before ordering to confirm a proper fit. This adapter is a Sierra 18-99402, part of Sierra's line of Evinrude outboard electrical system components.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-99402
• Category: Evinrude Outboard Electrical System
• Harness Length: 18 inches
• Weight: 0.7 pounds
• Compatible Engines: 1996-2016 Johnson and Evinrude outboard engines
• Adapts To Controls: 1976-1995 Johnson/Evinrude control systems
• UPC: 808282394837

Fitment

• Johnson/Evinrude outboard engines, 1996-2016, adapting to 1976-1995 control systems

Frequently Asked Questions

What does the Sierra 18-99402 adapter harness do? It connects a 1996-2016 Johnson or Evinrude outboard engine's wiring to a control system built for the 1976-1995 era, so the two can communicate without rewiring the boat's controls.

How long is the harness? The Sierra 18-99402 harness measures 18 inches, sized to route between the engine wiring loom and the boat's existing control harness.

How much does the 18-99402 weigh? It weighs 0.7 pounds.

Will this harness fit any Johnson or Evinrude engine? It is designed for 1996-2016 Johnson and Evinrude engines being adapted to 1976-1995 controls; Sierra recommends checking the part numbers recommended for your specific engine and control combination before ordering to confirm a proper fit.

Can I use this harness to connect an older control box to a newer outboard? Yes, that is the harness's purpose: adapting a newer (1996-2016) Johnson/Evinrude engine so it can work with an older (1976-1995) control system, which is useful when a powerhead is upgraded but the boat's controls are kept.

Is the Sierra 18-99402 rated for marine environments? Yes, the harness is built for use in a marine environment, where it is exposed to moisture, vibration, and temperature changes typical of an outboard engine compartment.

Does the 18-99402 include connectors on both ends? The harness is a complete adapter cable intended to plug in between the engine wiring and the boat's control wiring; check your engine and control part numbers against Sierra's fitment guidance to confirm connector compatibility.

What is the UPC for this part? The UPC for the Sierra 18-99402 wiring adapter harness is 808282394837.

Do I need any other parts to use this harness? No additional parts are specified; the 18-99402 is installed inline between the existing engine wiring and control wiring.

Is this harness only for Johnson and Evinrude engines? Yes, the Sierra 18-99402 is built specifically to adapt Johnson and Evinrude engine wiring to Johnson/Evinrude control systems.