MerControl wiring disintegrated

[zaetc]

Hi, my uncle gifted me his old boat with a Merc 1150 on it. The boat is from '80, can't find the motor year since it has a Canadian serial number.
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I was having problems with the throttle and opened the control unit. All the wires insulation is cracked leaving exposed copper.
Do I need to buy a whole new harness back to the motor? If so I'm having a hard time finding the correct one, maybe someone can help me with that? It's 6 pin.

Thank you

 

[gm280]

There are companies that make such harnesses but I don't have any suggestions as to who they are. Search the net and see. However, if only the wires in the control unit are having issues, is there any excess wire harness that you can cut off the bad wires and rewire with good insulated wires? If so, that is what I would try to do before buying a new harness. A new harness is certainly going to be a bit pricey I sure.

 

[Chris1956]

I just replaced the wiring in my '77 MerControl. It was much worse than the wires in your picture, FWIW.

You need to check the boat harness and see what condition it is in. Maybe, if it is a bit too long, you can pull some better wire forward.

There is more than just the wires from the boat harness in the MerControl. You will need single wires from ign switch to neutral switch, and power from ign switch to choke button. You also need power from ign switch to tach connector, plus ground and tach signal.

The maxrules web site will have a wiring diagram, but you will need to make some notes, as the ign switch has terminals labeled a,b,c,d,f,g rather than for the function of each terminal. So you will need a cheat sheet for that.

You will also need a powerful soldering iron. I used an 80W iron and it worked well, plus flux and radio solder.

The ign switch terminals have holes, so make sure to blow out the old solder so the new connections can be strong.

 

[zaetc]

Chris1956 I will try to see if I have enough extra cable when I get home from work. You said you replaced yours, did you just have extra like you suggested I try?
I found the 2006 wiring diagram although people say they changed the colouring scheme but I plan to write everything down as it's currently hooked up and take pictures.

If I don't have enough cable in the boat is it possible to open the harness and butt connect extensions onto it with new wires into the controller?
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[Chris1956]

I had extra cable that I was able to use.

You will need to use a wiring diagram from 1980 or so, as the newer ones show "Push to Choke" ignition switches with more terminals. Also, modern harnesses have more wires for overheat sensor and power trim

Wire colors could be different, as the changeover was about 1980.

You will also want to use an ohmmeter to verify the functions of each terminal on the ign switch, to make sure you have it right.

You can certainly extend the current harness. I would recommend flux, crimping and then sweat soldering the wires to the butt connectors. Then cover them with shrink tube insulation.

Some tips: The choke button gets power from the ign terminal, as does the tach connector. The neutral switch is soldered to a wire from the start terminal on the ign switch and to the solenoid wire (yellow or yellow/red) in the boat harness.