1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 44Get this manual
3 Cylinder Battery Charging Diagram with Battery Isolator IMPORTANT: After electrical connections are made, coat all terminal connections using Quicksilver Liquid Neoprene (92-25711), to avoid corrosionBLK BLU GRY RED YEL DBLACK DBLUE DGRAY DRED DYELLOW
Start Battery
Move Red Lead From Start Solenoid to Position Shown
User Supplied Red Lead (10 Gauge Minimum Diameter with Protective Abrasive Sleeve Installed)