Help Identifying Wiring on Trim for late 70s Mercruiser

[Twolane]

I recently got an old boat. I have a nice shop. Put one and one together and now friends think I'm a marine mechanic. Silly boys. A little help please if someone knows and would offer.

Buddy drug an old Mercruiser equipped boat out of long term storage. Trim goes down but doesn't go up (I think that's right). Pulled the dog house off and quickly saw this. If anyone can help identifying the purpose and source of what's here and what's missing it'd be appreciated.

Notice on the three wire plug to the trim pump only two wires are there. Looks like one has been snipped off smooth. Though I obviously can't sweat it's ever been there. Just above and marked with the other red arrow is an empty spot and what I assume is a breaker. Nothing on that post out at all.

In my hand and marked with the orange arrows are a pair of wires that were tied together and tucked inside the harness. The heavy purple has been broken just beyond the bullet type plug. The other is just unplugged. Am assuming they're a pair with the same destination since they were tied together. But couldn't find their mating connectors.

Thanks.

 

[Don S]

Re: Help Identifying Wiring on Trim for late 70s Mercruiser

Here is how it should be wired.

View attachment #2 Eng & Drives 74-77 199.pdf

 

[Twolane]

Re: Help Identifying Wiring on Trim for late 70s Mercruiser

Here is how it should be wired.

View attachment 162383

Thanks very much. That helps. Looks as if the three wire round plug on to the pump motor does just have two of the three wires used. Blue and green is illustrated in the schematic and is what's on this boat. The third wire one can tell would have been red but it's cut off smooth with the plug. Apparently not used in this application?

The currently unused blue and purple wires being held in the pic go to the trim limit switch. That's the little round switch on the left side of the gimbal? Looks like it'll be a PITA to replace but also an apparently obvious replacement. Already found a PDF with installation/adjustment instructions.

There is one wire location 'd questioned not covered in this schematic. There's a circuit breaker on the solenoid bracket. Power goes to the breaker from a short leg piggybacking off one of the solenoids. But nothing is attached to the breaker's outbound side.

I did find a light brown wire coming out of the engine harness that is about the right length to reach there and has the right sized eyelet. It runs inside the harness and goes around to the engine's left side. Only thing over there is the alternator (Delco). Might this breaker be a power feed to energize the alternator?

Just guessing for now obviously. Ordered an old OE Mercruiser service manual last week that's not here yet. Hopefully wiring diagrams in it will help with questions like this. But for now I'm sucking up to the more informed.