trim wiring

[flwestcoastal]

I would appreciate any help, as I have searched for hours online for to no avail. My boat is a 1992 which was equipped with a 1992 yamaha 40 2 stroke W/O PTT, which at some point was converted to premix. I assume the wiring harness was for the original engine. I later upgraded to a 2006 50 HP 2 stroke w PTT. I did buy a Trim & Tilt / Oil Level Sender Wire Harness Cable 20ft 6Y5-83653-10-00 so I could connect a yamaha analog tach i had bought (there was no tach or buzzer on boat when I bought it).

I connected the tach and it works fine. I have a yamaha 704 throttle but there are no wires to connect the trim wires to. I have seen pics of harnesses with dedicated connectors for the trim wires, but there is not one on my engine harness, and my 704 trim wires does not have connectors either. Am I missing something? Can I buy a connector to plug into the sender harness i used for my tach I listed above? Do I need a seperate wire run? Please help me out, I just cant figure this one out!

Thanks so much!!

[boscoe99]

If the boat has a 704 control box then it uses a key switch panel. The warning horn is located behind the key switch panel.

The 704 control box should have a trim and tilt switch mounted in the handle. By saying that the 704 control box has no wires to connect the trim wires to are you implying that the control handle does not have a switch installed?

See the attached diagram which should depict the configuration of your motor. Assumption being that this is a model that was sold in the US.

[99yam40]

I am begining to think he was trying to refer to trim angle maybe

[flwestcoastal]

I am not referring to the trim angle as i have no trim gauge installed. But I appreciate you responding. I looked behind the 704 key switch and there is a white wire cut along with a yellow wire connector not attached to anything. I can only assume the buzzer was cut out, or was installed on the original 40 hp 2 stroke outboard as there were 3 led lights (on the outboard) that had the wires cut when I bought it. My 704 has the trim switch and I believe they are brown wires (hard to see at night). If those are right what do I connect them to? Please note there are no special connectors. Being that I installed the tach, is there something I can attach to that wiring that will control the trim??

Thanks again, I appreciate all input!

[99yam40]

red(12 V +) to LT green or Lt blue to operate trim relay

[boscoe99]

The brown wires from the 704 control box are for the neutral safety switch. As 99yam notes, the three wires for the trim function are red, grass (down) green and sky (up) blue.

The tachometer in no way is connected to the engine trim system. Many many boats that have power trim and tilt don't have any gauges at all. The only commonality between the tachometer and the engine trim system is that the ten pin wire harness conveys 12 volt power to both the tachometer and the trim system. Via red wire.

The connections are all shown in the diagram above.

[rodbolt17]

and it is possible you only have a 7 pin harness from the console to the engine.
at the keyswitch do you see a red,light blue and light green wires from the main harness?
from the 704 do you see the same three wires?
not all 704 box's had a trim switch.

[flwestcoastal]

Yes, my engine harness has 10 pins, but only 7 wires at the helm end (previous owner replaced pt/t with a cmc, just maybe they snipped the 3 trim wires off). My 704 definitely has a factory trim switch along with the 3 wires (red,blue, and green). I Just cant find any wires from the engine harness to connect them. Is it possible the 7 pin still uses a 10 pin connector but does not include trim wires? (boat and motor when purchased were both 1992 and I can only assume both were original as well as wiring harness. Thanks again for the advice!

[boscoe99]

Yes, my engine harness has 10 pins, but only 7 wires at the helm end (previous owner replaced pt/t with a cmc, just maybe they snipped the 3 trim wires off). My 704 definitely has a factory trim switch along with the 3 wires (red,blue, and green). I Just cant find any wires from the engine harness to connect them. Is it possible the 7 pin still uses a 10 pin connector but does not include trim wires? (boat and motor when purchased were both 1992 and I can only assume both were original as well as wiring harness. Thanks again for the advice!

The 704 ten pin harness has one ten pin connector at the engine end and two connectors at the helm end. One connector having 8 pins and the other connector having six pins.

A 703 ten pin harness has one ten pin connector at the engine end and ten bullet connectors at the control box end.

My guess is that you need a new 704 ten pin harness. Which will plug and play with the engine at one end and the key switch and the control box at the helm end.

[flwestcoastal]

Thanks again for everyone helping me out. Due to the fact I do not have the time and money right now to replace the main harness, I hope to use the two trim wires from the previous CMC tilt that are still in place for my pt/t. We are very grateful for everyone helping us narrow down the problem. Happy New Year and tight lines!