1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 298Get this manual
Motor and Electrical TestsRepair Trim Pump Motor Test WARNING
Do not perform this test near flammable materials, as spark may occur while making electrical connections1Connect 12 volt power supply to motor wires [positive (+) to blue wire and negative (-) to black wire]Motor should runDisconnect blue wire and connect green wire to positive (+) terminal of power supplyMotor should run2If motor does not run, disassemble and check components
MOTOR DISASSEMBLY 1Remove screws and clamp
Solenoid Test WARNING
Do not perform this test near flammable materials, as spark may occur while making electrical connections1Disconnect all wires from solenoid terminals2Set an Ohmmeter to Rx1 scale and connect meter leads to solenoid terminals and 23Connect 12 volt power supply to terminals and 4Solenoid should click and meter should read zero (0) ohms (full continuity)a Screw (4) Screw (3) Clamp Grommet Gasket