1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 278Get this manual
ELECTRICAL SYSTEM TROUBLESHOOTING CONDITION OF TRIM SYSTEM ATrim motor does not run when trim button is depressedBTrim system trims opposite of buttonsCCowl mounted trim buttons do not activate trim systemPROBLEM
PROBLEM 1, 2, 4, 5, 6, 2, 4, 5, 6
1Battery low or discharged2Open circuit in trim wiring3Wiring reversed in remote control4Wire harness corroded through5Internal motor problem (brushed, shorted armature)6Blown fuse(s)7Trim Solenoids Failed