Sierra Wiring Harness 18-99431, Replaces 391818, Fits Johnson/Evinrude 2 Cyl Cross Flow 20-35 HP 1982-1984

The Sierra 18-99431 wiring harness is a direct-fit replacement wiring harness built for Johnson/Evinrude 2 cylinder Cross Flow outboard engines. It supplies the connector runs needed to link the engine's ignition and charging components to the control box and gauges, restoring a clean, factory-style electrical connection when an original harness has cracked, corroded, or failed. The harness is constructed of copper conductors insulated in PVC or PE jacketing, materials chosen for resistance to moisture, fuel vapor, and the vibration common in an outboard engine compartment. It uses a marine engine connector interface, allowing it to mate with the factory-style plugs on compatible powerheads without modification.

This harness replaces OEM part number 391818 and fits Johnson/Evinrude 2 cylinder Cross Flow outboards from 1982-1984 rated at 20, 25, 30, and 35 HP. Replacing a deteriorated wiring harness restores reliable continuity across the ignition circuit, helping eliminate intermittent starting, stalling, or charging issues traced to worn or brittle wiring.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-99431
• Replaces (OEM): 391818
• Material: Copper, PVC or PE
• Item Dimensions: 9 x 7 x 2.5 inches
• Weight: 0.6 pounds
• Connector Type: Marine Engine Connector
• UPC: 808282394622

Fitment

• Johnson/Evinrude 2 Cylinder Cross Flow outboards, 1982-1984, 20, 25, 30 and 35 HP

Replaces (OEM)

• 391818

Frequently Asked Questions

What engines does the Sierra 18-99431 wiring harness fit? The Sierra 18-99431 wiring harness fits Johnson/Evinrude 2 cylinder Cross Flow outboards from 1982-1984 rated at 20, 25, 30, and 35 HP.

What OEM part number does this harness replace? Sierra 18-99431 replaces OEM part number 391818 on compatible Johnson/Evinrude 2 cylinder Cross Flow outboards.

What is the Sierra 18-99431 harness made of? It is built with copper conductors insulated in PVC or PE jacketing, materials selected for durability against moisture and vibration in the engine compartment.

How much does this wiring harness weigh? The Sierra 18-99431 wiring harness weighs 0.6 pounds.

What are the dimensions of the harness? The harness measures 9 x 7 x 2.5 inches.

Does this harness use the factory connector? Yes, part number 18-99431 uses a marine engine connector designed to mate with the factory-style plugs on compatible Johnson/Evinrude powerheads.

Will this harness work on a 3 or 4 cylinder Johnson/Evinrude engine? No, the Sierra 18-99431 is built for 2 cylinder Cross Flow outboards only; a different harness is required for 3 or 4 cylinder applications.

Is this a new replacement part or a repair kit for the original harness? The 18-99431 is a complete new replacement wiring harness, not a repair kit for the original wiring.

Why would I need to replace the wiring harness on my outboard? A cracked, corroded, or brittle wiring harness can cause intermittent starting, stalling, or charging problems; replacing it with the Sierra 18-99431 restores a clean, continuous connection between the engine and control box.

Does the Sierra 18-99431 include connectors at both ends? Yes, the harness comes complete with its marine engine connector interface for connecting to the engine's ignition and charging components.

Is the Sierra 18-99431 an OEM part or an aftermarket replacement? The 18-99431 is an aftermarket replacement harness manufactured to replace OEM part number 391818 on the applicable Johnson/Evinrude engines.