{"product_id":"cdi-johnson-evinrude-to-mercury-adapter-cable-sierra-18-99478-marine-ignition-conversion-harness","title":"Sierra Adapter Cable 18-99478, Johnson Evinrude to Mercury Tachometer Wiring Adapter","description":"\u003cp\u003eThe Sierra 18-99478 is an adapter cable built to connect Johnson\/Evinrude outboard wiring to a Mercury tachometer or gauge setup. It is designed for boat owners and technicians who are pairing a Mercury-style gauge with a Johnson or Evinrude outboard's electrical system, allowing the tachometer signal to be read correctly without rewiring the engine harness or the gauge itself. This type of adapter is a common solution when a gauge set is being upgraded, repowered, or mixed between brands, since Johnson\/Evinrude and Mercury tachometers are not wired to a common standard.\u003c\/p\u003e\u003cp\u003eThe cable is part of the Evinrude Outboard Electrical System category and is intended as a straightforward, plug-style connection point between the outboard's wiring harness and the gauge side, helping avoid cutting or splicing factory wiring. Keeping the adapter in line also makes future troubleshooting or component swaps easier, since the original harness and gauge wiring remain intact.\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 18-99478\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Name:\u003c\/strong\u003e Johnson Evinrude to Mercury Adapter Cable\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCategory:\u003c\/strong\u003e Evinrude Outboard Electrical System\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282396503\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 1.6 pounds\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-99478 adapter cable do?\u003c\/strong\u003e It connects a Johnson or Evinrude outboard's wiring to a Mercury-style tachometer or gauge, letting the two systems communicate without modifying the factory harness or gauge wiring.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this cable work with any Mercury gauge?\u003c\/strong\u003e The 18-99478 is built specifically as a Johnson Evinrude to Mercury adapter cable, but exact gauge and engine compatibility beyond that pairing is not specified, so confirm your gauge and outboard model before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-99478 adapter cable weigh?\u003c\/strong\u003e The Sierra 18-99478 weighs 1.6 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this an OEM Johnson\/Evinrude or Mercury part?\u003c\/strong\u003e The 18-99478 is sold under the Sierra part number and is not listed with any OEM cross-reference numbers.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I need to cut or splice my boat's wiring to install this adapter?\u003c\/strong\u003e No, the 18-99478 is designed as an in-line adapter cable so it connects between the existing outboard harness and gauge without splicing factory wiring.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat category of part is the Sierra 18-99478?\u003c\/strong\u003e It is listed under the Evinrude Outboard Electrical System category, reflecting its role as a wiring adapter for outboard gauge systems.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan this adapter cable be used to upgrade or repower a boat with mismatched gauges?\u003c\/strong\u003e Yes, an adapter like the 18-99478 is typically used when a Mercury gauge is being paired with a Johnson or Evinrude outboard, such as during a repower or gauge upgrade.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when I order the 18-99478?\u003c\/strong\u003e The order includes the Sierra 18-99478 Johnson Evinrude to Mercury adapter cable itself; no additional gauges or harness components are specified as included.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-99478 a universal adapter for all Johnson and Evinrude engines?\u003c\/strong\u003e Specific engine models or year ranges are not listed for the 18-99478, so fitment should be confirmed against your particular Johnson or Evinrude outboard and Mercury gauge before purchase.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat UPC is associated with the Sierra 18-99478?\u003c\/strong\u003e The Sierra 18-99478 adapter cable carries UPC 808282396503.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988444721371,"sku":"SIE-18-99478","price":206.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/CDI-423-9510_lg__37591.1558111666.500.750.jpg?v=1785329149","url":"https:\/\/www.goodvibesmarina.com\/products\/cdi-johnson-evinrude-to-mercury-adapter-cable-sierra-18-99478-marine-ignition-conversion-harness","provider":"Good Vibes Marina","version":"1.0","type":"link"}