Trim motor wiring

[Newguy1330]

I have a 1977 Silver line with a mercruiser 140 alpha one motor. Had some trim issues so I had the motor rebuilt and replaced the solenoid. Everything worked perfect in the driveway. Take the boat to the dock and get it in the water and i lose all trim. I get nothing from the motor. On top on the trim motor on the front is a screw. The wire connected to this runs to the back of the boat and connected to another wire that runs to the drive I think. The wire disconnected and I can't reconnect it. What is that wire and can it be connected to something else? I thought it was a ground but I'm not sure. All the wiring diagrams I have found only show the black, green and blue wires coming from the motor. Nothing from this screw. Help!!

 

[achris]

If a dedicated ground (black) wire hasn't been run (VERY bad!), the system may have been using that continuity grounding wire as the voltage return (even worse).... Find some black wire of about the same thickness as the large red wire and run that from the black on the trim pump (and solenoid) directly to the battery negative terminal.

Chris......

 

[Bt Doctur]

You need a #6 red wire to the battery and a #6 black wire to the battery or engine block

 

[Newguy1330]

The ground wire that comes from the trim motor is attached to the solenoid. Which then also grounds out to the same place as the battery. This wire is not permanently attached to the trim motor like the rest. It was attached to the screw that comes from the trim motor, that the plate the solenoid attaches to goes around to secure it. Same thing or different? The only reason I think it's a ground is of i touch it to a power, I get a large spark. I attached it to other grounds and get nothing.

 

[Newguy1330]

It is the single screw on the top with no wires. It would not let me load a picture from my phone.

 

[Bt Doctur]

The #6 ground wire is attached to the metal housing plate that supports the trim motor and goes to the battery.
The thick wire from the pump motor is bolted to this same plate.
The small ground wires from the solenoids are grounded to this plate.
The heavy blue and heavy green wires are attached to the top studs of the solenoids
Do you have this type of pump
http://www.boatfix.com/merc/Servmanl/14/14a5.pdf

 

[Newguy1330]

No my pump does not look like that. It's the same style as the link I posted above.

 

[Bt Doctur]

OK, this is the single solenoid one/ the black motor wire can go to the stud that mounts the solenoid. The #6 black wire from the battery can also go there. the small ground wires from the solenoids go there .the blue motor lead(up) goes to one side of the solenoid and the green motor lead(down) goes to a plastic block to the right of the solenoid and takes the small green control wire. The main 12v feed (#6 Red) goes to the left side and has the small red wire with the fuse .