76' Merc 175hp Black Max Trim Wiring Help

[First Attempt]

Hello, i just bought a 1973 Hydrostream vector with a 1976 Merc Black Max in great condition. The only problem is the trim dosen't work because the wiring from the hydraulic pump for the trim is all messed up. I'm trying to rewire it but can't find a schematic or diagram for the pump and don't know which wires do what. Any suggestions? Any advice, diagrams, or past experiences would be greatly appreciated. Thanks

 

[Chris1956]

Re: 76' Merc 175hp Black Max Trim Wiring Help

First, Are you sure it is a 1976 motor. I didn't think Merc made a 175HP that year.

That motor has the pump mounted in the boat, correct? If so, it will have a solenoid for running the motor in the up direction. It probably doesn't have a solenoid for the down position. The round, three wire connedtor feeds power to the trim button panel. The panel has three buttons. You must push the top and middle together to trailer the motor. Bottom button is down. The middle button is wired thru the trim limit switch(for trimming the motor up), which is probably faulty. If so, do yourself a favor and wire the middle switch directly to the up solenoid primary winding. Wire the bottom switch to the down wire. The black wire is common to the up and down motor circuit, and should be grounded.

 

[First Attempt]

Re: 76' Merc 175hp Black Max Trim Wiring Help

I'm just going out to try what u said to do, but it has a solenoid for the down as well as the up, would wiring it be any different? If i can, i'll post a picture a litttle later.

 

[Chris1956]

Re: 76' Merc 175hp Black Max Trim Wiring Help

The 2 solenoid trim pumps are later models than the one solenoid pumps. You might get the correct year of your motor, just so you can get the correct parts if needed. The wiring is the same however instead of the down wire being connected directly to the motor, it is connected to the down solenoid, on your setup.