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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10806
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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I need the wiring diagram for a Mercruiser Pre Alpha Tilt/Trim

Customer Question

I need the wiring diagram for a Mercruiser Pre Alpha Tilt/Trim lift Pump, I am not sure it is wired correctly. I have replaced the switch on the handle but the pump only works on the green side of the switch, the blue side will not operate the pump. The previous owner changed out some of the wiring but I don't know if he put it in the correct positions on the solinoid. Is There a schematic for this pump? How is the solinoid suppose to be wired to the pump motor? Can the pump be bad? Am I wasting my time with this pump or how dependable is it? I do appreciate any answer I can get. Thank You!!!
Submitted: 7 years ago.
Category: Boat
Expert:  Tan replied 7 years ago.
Hi, Do you have one solenoid and a 3wire motor? Blue ,green, black.
Customer: replied 7 years ago.

Yes, I only see the one solinoid, there are three wires that come from the handle switch, the wiring was changed by the previous owner so the wires may not be correct but have voltage to the switch, it is a three wire motor, power, blue for up and green for down and red for power from the switch.

The solinoid has several wires and there is a relay for the black wire which is also the blue wire i believe but not sure.

Expert:  Tan replied 7 years ago.
The solenoid should have 12 volt power supply on large wire from the pump motor to the opposite large term. The 2 small terminals on solenoid one blue wire from the switch. The other terminal ground. The black wire on pump motor to ground. The green wire from switch connects to the green wire of the motor. Now the trim should work. Thanks click "Accept" button.Post back with questions..Tan
Customer: replied 7 years ago.
Tan, what I need is a schematic for the pump. There are wires that are attached to the pump motor, a relay and the sloinoid. The wiring information you gave me is for the switch from the handle, when I bought the switch it had its directions, but I am not sure if the solinoid id wired correctly to the pump motor itself.
Expert:  Tan replied 7 years ago.
Mercury only used relays or solenoids not together. The wiring that I gave you is for the solenoid for mercury t-n-t. Is this your unitDiagram of Mercury Mercury Outboard Parts 115 (6 CYL.)(NNN) NNN-NNNNTHRU(NNN) NNN-NNNNPOWER TRIM COMPONENTS (WITH CIRCUIT BREAKER AND FUSE) Diagram? If you could get a serial number that would help. Tan

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