1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 323Get this manual
Troubleshooting the "Down" Circuit (When "Up" Circuit is OK) Remote Control Not Equipped with Trailer Button
Connect Voltmeter red lead to Point and black lead to groundDepress the "Down" trim button
No Voltage Indicated: Battery Voltage Indicated: Down Relay is DefectiveReplace and retestConnect Voltmeter red lead to Point and black lead to groundDepress "Down" trim buttonIf battery voltage is indicated, wire is open between Points and 1
No Voltage Indicated: Connect Voltmeter red lead to Point 5If battery voltage is indicated, trim switch is faultyIf no battery voltage, check for loose or corroded connection at Point or open circuit in wire supplying current to Point 5
Troubleshooting the "Up" Circuit (When "Down" Circuit Is OK)