1975 Johnson 115 Tilt trim question

crb478

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Dec 6, 2006
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I have learned a lot from many of you out there and I hope that you can help me with my latest problem. The amount of knowledge on this board is unbelievable.
I recently picked up a 1975 Johnson 115 model number 115ESL75E that was not running and had had the tilt and trim removed from the motor. The prior owner had sold the boat trailer and I grabbed the motor and the controls that were there before the boat and trailer were towed away. These did not include the tilt trim motor controls. I got the motor started/running without to much trouble and I will rebuild the carbs and put in a new water pump kit over the winter and see just how well I can get it to run.
I had the tilt trim motor (prestolite) repaired at an electrical shop and it now works again, but I just have the three wires comming out of the motor to work with. I have a clymers manual and read that one cylinder is for trim and the other for tilt. Is this right?
I have the motor mounted on a stand right now and I can not hook up the tilt trim because one of the stands legs is in the way. I can add 12V to the black and blue wires and one cylinder will extend fully but the other just a few inches. If I then use the black and red wires the same cylinder that will extend fully will also retract fully, but the other one will not. Is this normal? Would the weight of the engine simply push this cylinder back in as it came down? There is also a wire that goes into the back of that cylinder. Does anyone know what that wire is for? Right now it has been cut and is just hanging.
Lastly what do I need to make this work on my boat. I noticed that the factory harness is much more complex than just using a switch to run the motor in different directions, but would anything be damaged just supplying 12V to either the red or the blue wires as long as they were not held down once the upper and lower limits were reached? I would like to tie it into my rocker switch on my current controls if possible and raise and lower the engine from the console. Sorry for the long post.
Thanks for any thought or suggestions.
 

HighTrim

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Jun 21, 2007
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10,486
Re: 1975 Johnson 115 Tilt trim question

Here is how you need to wire it, let us know if you have any other questions. As you can see , the black 16 ga wire coming off the cylinder is for the trim gauge.

trim wiring red blue black.jpg
 

crb478

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Re: 1975 Johnson 115 Tilt trim question

Thanks for the diagram. What is the purpose of the solenoid in this situation? I will have to recreate everything needed since it came without any of the wiring harness. Thanks Again
 

HighTrim

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Jun 21, 2007
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10,486
Re: 1975 Johnson 115 Tilt trim question

The trim motor is usually a DC motor and it's direction is controlled by the direction of current flowing through it. Run it through one way and you go up, reverse it and you go down.

The solenoid, very close to, if not exactly the same thing that starts your outboard and your automobile, is used to supply the current in opposite directions to the trim motor.

It is a magnetically controlled "contactor".....very high current switch. When you put a small current through the control windings, it energizes the solenoid coil which pulls in the high current contacts.

When this happens, it is abrupt and you can normally hear and feel it (with your hand on the body). It may be silent, but usually not. If anything, silence would be an indication of friction in the circuit (inside the thing) not allowing the contactor to move freely.
 

HighTrim

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Jun 21, 2007
Messages
10,486
Re: 1975 Johnson 115 Tilt trim question

Look at this site for anything that you need to complete if you cannot locate it, the guy is in Florida and has been pretty good to me. He ships ASAP.

"http://www.maxrules.com/fixomctrim.html"
 

crb478

Lieutenant Junior Grade
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Dec 6, 2006
Messages
1,036
Re: 1975 Johnson 115 Tilt trim question

Not that I am trying to out think the engineers who designed the system because I am sure that they forgot more than I ever learned, but it seems like you should be able to have 12V comming into the center of a switch and then the top position would go to the blue wire to raise the motor and the bottom position would go to the red wire which would lower the motor.
Would it work this way? I don't want to spend more than I need to, but I don't want to damage anything either. I see the wiring harnesses for the older motors on ebay ocassionally, but they usually go for top dollar.
A CMC might actually be cheaper in the long run, but I would like to get this one going if reasonably possible. Thanks
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: 1975 Johnson 115 Tilt trim question

Send me a private message with your email and I will mail you some optional wiring and ideas if you want. I cant post them on here due to their size.
 
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