Johnson Evinrude Outboard Motors 1956-1970 1.5-40hp repair manual., Page 166Get this manual
IGNITION
WIRING HARNESS CRITICAL WORDS: These next two paragraphs may well be the most important words in this chapterMisuse of the wiring harness is the most single cause of electrical problems with outboard power plantsA wiring harness is used between the key switch and the engineThis harness seldom contains wire of sufficient size to allow connecting accessoriesTherefore, anytime new accessory is installed, NEW wiring should be used between the battery and the accessoryA separate fuse panel MUST be installed on the dashTo connect the fuse panel, use one red and one black No10 gauge wires from the batteryIf small amount of 12-volt current should be accidently attached to the magneto system, the coil will be damaged or DESTROYEDSuch mistake in wiring can easily happen if the source for the 12-volt accessory is taken from the key switchTherefore, again let it be said, NEVER connect accessories through the key switchThe wiring harness installed on the 35 hp, 1959, and the 40 hp, 1960 model units, was connected to the the side of the engine through an electrical plug utilized "male" 'and "female" connectorsThis particular type connector has been contributing factor to number of problems in the ignition system due to the suceptibility of the connector to corrosionThe plug is exposed and subject to moisture which is especially des-