1986+ Mercury 6/8/9.9/10/15HP 2-stroke Factory Service Manual, Page 212Get this manual
POWER TRIM
Troubleshooting the Up Circuit
Connect Voltmeter RED lead to Point and black lead to groundDepress the Up trim button
No Voltage Indicated: Battery Voltage Indicated: Connect Voltmeter RED lead to Point 9Connect Voltmeter RED lead to Point and BLACK lead to groundDepress Up trim buttonIf battery voltage is indicated, wire is open between Points and 8No Voltage Indicated: There is an open circuit between Point and positive (+) battery terminalCheck for loose or corroded connectionsCheck wires for open circuitBattery Voltage Indicated: Test DOWN relayRefer to Power Trim Relay Test ProcedureNo Voltage Indicated: Relay Switch is defective