{"product_id":"marine-wiring-harness-for-johnson-evinrude-20-25-35-hp-outboards-1977-1981-replaces-oem-389269-round-plug-2-cylinder","title":"Sierra Wiring Harness 18-99422 for Johnson\/Evinrude 20, 25, 35 HP Round Plug Outboards, 1977-1981","description":"\u003cp\u003eThe Sierra 18-99422 is a replacement engine wiring harness built for Johnson and Evinrude outboards that use a round plug connector. It carries the main engine-to-control wiring for 20 HP, 25 HP, and 35 HP round-plug outboards from the 1977-1981 model years, giving owners a direct way to restore or replace deteriorated, cracked, or corroded factory wiring without splicing in a universal harness. Marine wiring harnesses like this one are a common failure point on older outboards, since constant vibration, saltwater exposure, and UV exposure break down the insulation and connector contacts over time, leading to intermittent gauges, stalling, or a no-start condition. Installing a correctly matched harness restores factory-style connections at the engine and control box, keeping the wiring routed and terminated the way the outboard was originally designed.\u003c\/p\u003e\u003cp\u003eThis harness is a direct fit for the listed Johnson\/Evinrude round plug engines and is cross-referenced to the OEM wiring harness numbers below, so it installs in place of the original part without modification. It ships as a single, complete harness assembly ready to connect at both ends.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-99422\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCategory:\u003c\/strong\u003e Evinrude Outboard Electrical System\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.7 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConnector Type:\u003c\/strong\u003e Round Plug\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eItem Dimensions (L x W x H):\u003c\/strong\u003e 7 x 9 x 2.5 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNumber of Items:\u003c\/strong\u003e 1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282394530\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eJohnson\/Evinrude 20 HP, 25 HP, and 35 HP outboards with a round plug connector, 1977-1981\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e389269\u003c\/li\u003e\n\u003cli\u003e387872\u003c\/li\u003e\n\u003cli\u003e389764\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-99422 wiring harness fit?\u003c\/strong\u003e It fits Johnson\/Evinrude outboards with a round plug connector in 20 HP, 25 HP, and 35 HP, model years 1977-1981.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-99422 harness a direct OEM replacement?\u003c\/strong\u003e Yes, Sierra 18-99422 is a direct replacement that installs in place of the original harness without modification, using the same round plug connection.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does 18-99422 replace?\u003c\/strong\u003e It replaces OEM numbers 389269, 387872, and 389764 on the covered Johnson\/Evinrude round plug outboards.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the wiring harness weigh?\u003c\/strong\u003e The Sierra 18-99422 wiring harness weighs 0.7 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the dimensions of the harness as packaged?\u003c\/strong\u003e The 18-99422 harness measures 7 x 9 x 2.5 inches.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat type of connector does this harness use?\u003c\/strong\u003e Sierra 18-99422 uses a round plug connector, matching the factory setup on the covered 20, 25, and 35 HP Johnson\/Evinrude engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this harness work on a square plug outboard?\u003c\/strong\u003e No, the 18-99422 is built for round plug engines only; a square plug outboard requires a different harness.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many harnesses come in the package?\u003c\/strong\u003e One complete wiring harness assembly ships per package (18-99422).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes replacing the wiring harness require cutting or splicing?\u003c\/strong\u003e No, because 18-99422 is a direct-fit replacement for the OEM harness, it connects using the original round plug terminations without cutting or splicing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat symptoms indicate a Johnson\/Evinrude outboard needs a new wiring harness?\u003c\/strong\u003e Cracked or corroded insulation, intermittent gauge readings, stalling, or a no-start condition on a 1977-1981 round plug engine often point to a failing harness, which the 18-99422 is designed to replace.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this harness only for Evinrude, or does it also fit Johnson engines?\u003c\/strong\u003e It fits both Johnson and Evinrude outboards, since the two brands shared the same round plug engine electrical systems covered by part 18-99422.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988443476187,"sku":"SIE-18-99422","price":178.81,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/CDI-413-9914_lg__45873.1558112658.500.750.jpg?v=1785188564","url":"https:\/\/www.goodvibesmarina.com\/products\/marine-wiring-harness-for-johnson-evinrude-20-25-35-hp-outboards-1977-1981-replaces-oem-389269-round-plug-2-cylinder","provider":"Good Vibes Marina","version":"1.0","type":"link"}