1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 331Get this manual
3Remove O-rings from cylinder Motor and Electrical TestsRepair
Trim Pump Motor Test WARNING
Do not perform this test near flammables (or explosives), as spark may occur when making connections1Disconnect GREEN (motor) wire and BLUE (motor) wire from trim system wiring harness51008
aO-rings
Cleaning and Inspection of Trim Rod Components
CAUTION
Do not remove check ball components (a) from trim rod pistonRemoval and re-installation of check valve could result in improper operating pressure and possible power trim system damage
2Connect 12 volt power supply to motor wires (POSITIVE to BLUE; NEGATIVE to GREEN results in motor up directionPOSITIVE to GREEN; NEGATIVE to BLUE results in motor down direction)Motor should run3If motor does not run, disassemble motor and check components