Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 289Get this manual
Solenoid Test DO NOT perform this test near flammables (or explosives), 8S spark may occur when making connectionsNOTE: Two different style solenoids have been used on the trim pumpWhen connecting Ohmm eter and battery leads refer to the appropriate photo (depending on wh ich style solenoid is being tested) forterminal identification
1Disconnect all wires from solenoid terminals2Use an Ohmmeter (Ax1 scale) and connect meter leads between solenoid terminals and 23Connect 12-volt supply between solenoid terminals and 4Solenoid should click and meter should read zero ohms (full continuity)
4If meter does not read zero oh ms (full continuity), replace solenoid