Sierra Wiring Harness 18-99389, OMC 0393590 Cross Reference, Fits 1985 Evinrude Johnson 120/140 HP Outboards

The Sierra 18-99389 is an internal engine wiring harness (cable assembly) built to connect the electrical components of the powerhead on covered Evinrude, Johnson, and OMC outboards. It is constructed with copper wiring for reliable current flow and electrical continuity between the engine's ignition and electrical components. Wiring harnesses like this one are a common replacement item on older outboards, since insulation and connector points degrade with heat cycling, vibration, and years of exposure to a marine engine compartment. Installing a fresh harness restores a clean, factory-style wiring path and helps eliminate intermittent electrical faults caused by a deteriorated original harness.

This harness is cross-referenced to the OMC part number 0393590 and is intended to fit 1985 Evinrude, Johnson, and OMC outboards rated at 120 and 140 HP. Always confirm your engine's horsepower rating and model year against the fitment listed below before ordering, since wiring harnesses are engine-specific and the wrong harness will not connect correctly.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-99389
• Material: Copper
• Weight: 0.7 pounds
• UPC: 808282398880
• OEM Cross Reference: 0393590
• Fitment: Evinrude, Johnson, and OMC 120 and 140 HP outboards (1985)

Fitment

• Evinrude 120 HP outboard, 1985
• Evinrude 140 HP outboard, 1985
• Johnson 120 HP outboard, 1985
• Johnson 140 HP outboard, 1985
• OMC 120 HP outboard, 1985
• OMC 140 HP outboard, 1985

Replaces (OEM)

• 0393590

Frequently Asked Questions

What engines does the Sierra 18-99389 wiring harness fit? The Sierra 18-99389 is designed for 1985 Evinrude, Johnson, and OMC outboards rated at 120 and 140 HP.

Is the Sierra 18-99389 the same as OMC part number 0393590? Yes, the Sierra 18-99389 wiring harness cross-references directly to OMC part number 0393590.

What material is the wiring harness made from? The internal wires in the Sierra 18-99389 harness are copper, chosen for reliable electrical conductivity in an engine compartment environment.

How much does the Sierra 18-99389 wiring harness weigh? It weighs 0.7 pounds.

Will this harness fit a 1985 Johnson 140 HP outboard? Yes, the Sierra 18-99389 is listed to fit 1985 Johnson outboards in the 120 and 140 HP range.

Does this harness work on OMC-branded outboards, not just Evinrude or Johnson? Yes, the fitment for the Sierra 18-99389 covers Evinrude, Johnson, and OMC 1985 outboards at 120 and 140 HP, since these brands shared engine platforms during that era.

Why would I need to replace the internal wiring harness on my outboard? An internal wiring harness like the Sierra 18-99389 connects key electrical components on the powerhead, and it is commonly replaced when the original harness has degraded from age, heat, or vibration, causing intermittent electrical issues.

What is included when I order the 18-99389 harness? The order is for the Sierra 18-99389 internal wiring harness (cable assembly) itself, sized for 1985 Evinrude, Johnson, and OMC 120/140 HP outboards.

Is the UPC for the Sierra 18-99389 harness listed anywhere? Yes, the Sierra 18-99389 wiring harness carries UPC 808282398880.

Can I use the 0393590 cross-reference number to confirm compatibility with my engine's original harness? Yes, if your engine's original harness is OMC 0393590, the Sierra 18-99389 is the cross-referenced replacement for it.