merc 120 wiring and trim wires

[shawnhowell]

OK folks this is my self intro to both boating and this forum. I'm Shawn and I just got my first boat. It's old and broken, but a good foundation. I'm going through all the wiring because it's all gotten pretty hacked up over the years, and I don't really want to get stranded in the middle of lake Ontario here in NY.

There's a few things I'm a little confused about, and can't find much info yet.

1)What are the 3 buttons on the Trim control panel for?
I know they raise and lower the outboard, but what is the 3rd button for?
The buttons are labeled from top to bottom:Up, Up, Out, Down with the
middle button straddled by the Up, and Out. I can post a pic of the front
and back of the3 switch if necessary. It has been re-wired, and I doubt
the talant of the previous owner.

2)Should I have to press the top two buttons at the same time to raise the outboard?
When I press the top two together the outboard comes up, and the
bottom one by itself lowers it back down.

3)What are the two wires running from the trim control panel out through the transom to the outboard for, and are they a huge pain to replace?
One of the wires is Violet, and the other is Light Blue, and they seem to
be heavier guage than most of the rest. They run through the transom
about 4 inches above the water pipe, and are extremely dry rotten. Again
I don't want to end up stranded.

 

[achris]

Re: merc 120 wiring and trim wires

Hi and welcome to the forum... You'll have fun....

The 3 switches are as follows. (and this will answer you're question about the wires that run through the transom).

The bottom button, DOWN, is for lowering the outdrive.
The centre button is to raise the outdrive to the point where the trim limit switch opens (located inside the bellhousing on the outdrive.)
Once the outdrive is trimmed up to the limit (usually about a third of the way up) you'll need to press the centre button AND the top button together to get the drive to raise all the way up.

Usually the wires that run to the limit switch rot out, and most people just link the terminals together., so the centre button will take the drive all the way up.

Cheers, good luck and I hope this helps...

Chris.............

 

[shawnhowell]

Re: merc 120 wiring and trim wires

Thanks for the quick response. That certainly does answer some questions, but I'm not officially a boater yet, so I have a couple more. I'm assuming the trim limit switch is something the factory installs and a qualified mechanic adjusts as a safety feature. It basically keeps the bow in the water, or close to it right? I guess the real question is would it be worth while replacing for a newbie boater with kids on board? I have to pull the outboard to replace all three bellows anyway (not sure I wanna experience bailing water on my first trip out).

 

[achris]

Re: merc 120 wiring and trim wires

Without knowing the age of the engine I can't advise you... The older style are no longer available. As I said in my first post, most people just link out the switch so the centre button will run the drive all the way up. Yes, it is a feature engineered in by Merc, but it was to stop high sideways loads being applied to the drive when it was outside the supports, nothing to do with safety. I also believe that someone would have to be a complete moron to be running at speed and try to trim the leg all the way up.... But I have been wrong before....

Cheers,

Chris..............

 

[shawnhowell]

Re: merc 120 wiring and trim wires

I can't be completely sure of the year of the engine myself yet as I'm still working on getting the papers for this old beast, but I think I've narrowed it down to the 1972-1983 model. In any case I get the point. I just had to be sure of it's purpose before deciding to eliminate it considering I'll be having my family on there. I may even let my wife drive someday. She'd be the one out there trying to take off with the trailer still hanging from the bottom of the boat. Every safety feature helps. Thanks again for the quick reply, and all the help.

 

[achris]

Re: merc 120 wiring and trim wires

Women driving boats!!! Next they'll be wanting to vote!!! IT MUST BE STOPPED!!!

 

[bigbob_FTW]

Re: merc 120 wiring and trim wires

its not unsafe to run them this way, but you don't want to trim too far up. you'll end up striking the bellhousing with the u-joints. I recently replaced these switches when I installed a new bellow. Its a pain to get to for sure.