{"product_id":"sierra-18-99420-wiring-harness-for-mercury-mariner-outboards-replaces-84-76295-fits-20-hp-2-cyl-and-50-80-85-hp-4-cyl-1976-1981","title":"Sierra Wiring Harness 18-99420 - Replaces 84-73369 - Mercury\/Mariner 20 HP (1977-1981), 50\/80\/85 HP (1976-1979)","description":"\u003cp\u003eThe Sierra 18-99420 is a wiring harness engineered for Mercury\/Mariner outboard engines, built with copper conductors for reliable electrical continuity between the engine and control system. It is designed to fit 20 HP (2 cylinder) outboards from 1977-1981 as well as 50, 80, and 85 HP (4 cylinder) outboards from 1976-1979. The harness uses spade-style connectors for a secure, corrosion-resistant connection point and is designed to exit through the side of the lower cowling, matching the factory routing on these engines.\u003c\/p\u003e\u003cp\u003eThis harness is a direct replacement for a number of original Mercury\/Mariner part numbers, making it a straightforward swap for boat owners dealing with a cracked, corroded, or failed factory harness. Copper wiring construction supports dependable current flow to ignition and charging components, helping restore consistent engine electrical performance. The 18-99420 measures 7 x 9 x 2.5 inches and weighs 1.3 pounds, and it ships as a single complete harness ready for installation.\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 18-99420\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Copper\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConnector Type:\u003c\/strong\u003e Spade\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eItem Dimensions:\u003c\/strong\u003e 7 x 9 x 2.5 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 1.3 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCable Type:\u003c\/strong\u003e Auxiliary\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHarness Exit:\u003c\/strong\u003e Side of lower cowling\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUnit Count:\u003c\/strong\u003e 1 harness\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMercury\/Mariner 20 HP (2 cylinder), 1977-1981\u003c\/li\u003e\n\u003cli\u003eMercury\/Mariner 50, 80, and 85 HP (4 cylinder), 1976-1979\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e84-76295\u003c\/li\u003e\n\u003cli\u003e84-76295A1\u003c\/li\u003e\n\u003cli\u003e84-73447\u003c\/li\u003e\n\u003cli\u003e84-73447A1\u003c\/li\u003e\n\u003cli\u003e84-64997\u003c\/li\u003e\n\u003cli\u003e84-73369\u003c\/li\u003e\n\u003cli\u003e84-73369A1\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-99420 wiring harness fit?\u003c\/strong\u003e The Sierra 18-99420 fits Mercury\/Mariner 20 HP (2 cylinder) outboards from 1977-1981, and Mercury\/Mariner 50, 80, and 85 HP (4 cylinder) outboards from 1976-1979.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-99420 a direct replacement for the original Mercury harness?\u003c\/strong\u003e Yes, the Sierra 18-99420 is designed to replace the OEM Mercury\/Mariner harness on the applicable engines, with a matching electrical layout for a direct fit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich OEM part numbers does the 18-99420 cross-reference?\u003c\/strong\u003e The Sierra 18-99420 replaces Mercury\/Mariner part numbers 84-76295, 84-76295A1, 84-73447, 84-73447A1, 84-64997, 84-73369, and 84-73369A1.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the wiring made from?\u003c\/strong\u003e The 18-99420 harness uses copper wiring, which provides reliable conductivity for engine electrical circuits.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow big is the 18-99420 wiring harness?\u003c\/strong\u003e This harness measures 7 x 9 x 2.5 inches and weighs 1.3 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat type of connectors does this harness use?\u003c\/strong\u003e The Sierra 18-99420 is fitted with spade-style connectors for making secure electrical connections at the engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow does the harness route through the engine cowling?\u003c\/strong\u003e On the applicable Mercury\/Mariner engines, the 18-99420 harness is designed to exit through the side of the lower cowling, matching the original factory routing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this harness fit a Mercury outboard outside the listed year ranges?\u003c\/strong\u003e The 18-99420 is specified for Mercury\/Mariner 20 HP (2 cylinder) engines from 1977-1981 and 50\/80\/85 HP (4 cylinder) engines from 1976-1979; fitment outside those years is not confirmed, so buyers should verify against their engine's original part number before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-99420 come as a complete harness?\u003c\/strong\u003e Yes, the 18-99420 ships as a single complete wiring harness ready to install, with a unit count of one.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs Sierra 18-99420 a genuine Mercury part or an aftermarket replacement?\u003c\/strong\u003e The 18-99420 is a Sierra-brand replacement harness built to match and replace the original Mercury\/Mariner factory harness, rather than being sold under the Mercury brand itself.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy would I need to replace my outboard's wiring harness?\u003c\/strong\u003e Wiring harnesses like the Sierra 18-99420 are typically replaced when the original harness has cracked insulation, corroded connectors, or intermittent electrical faults affecting ignition or charging circuits on the applicable Mercury\/Mariner engines.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988443705563,"sku":"SIE-18-99420","price":235.62,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/CDI-414-3369_lg__52331.1722514870.500.750.jpg?v=1785188105","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-99420-wiring-harness-for-mercury-mariner-outboards-replaces-84-76295-fits-20-hp-2-cyl-and-50-80-85-hp-4-cyl-1976-1981","provider":"Good Vibes Marina","version":"1.0","type":"link"}