78 Evinrude 3 Wire Tilt/Trim Wiring

gnt530118

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I have been searching the forums for awhile and have not found the exact answer i'm looking for so hopefully someone can help. I have a 78 Evinrude 115Hp outboard model 115899C. The last owner cut off the trim wires at the motor. I cannot find any solenoid box or trim switch anywhere not even on the control box. What I was planning on doing was install a trim switch on the dash and rewire it. I know for this year it was hooked up by the solenoid and not the relay box. I have 1 new solenoid and the switch. However I can't find a wiring diagram to do it. I seen one that had 2 solenoid hook up. and also one diagram that did use the single solenoid but I don't have the terminal strip or any of the other wires that were in the diagram From my research or what I was thinking that the up switch is the one that needs the solenoid and the down can just be hooked up to the trim motor. I could be wrong. Does anybody have a wiring diagram I could see or explain how I can hook this up the correct way. Any help would be great! thanks
 

HighTrim

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Re: 78 Evinrude 3 Wire Tilt/Trim Wiring

This should help

Trimwiring.jpg
 

gnt530118

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Re: 78 Evinrude 3 Wire Tilt/Trim Wiring

This should help

Trimwiring.jpg

This is were I'm confused with this diagram. The top right picture around the solenoid with the what looks like an electrical strip. I don't have all those wires or connectors to the throttle control.

Can I just hook up the solenoid from a separate tilt/trim switch to the solenoid then back to the trim motor.
If so do you have to have 2 for that way or can do it with 1 solenoid, there was a drawing on the forum that has 2 solenoids so I was just checking

Thanks for the reply
 

gnt530118

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Re: 78 Evinrude 3 Wire Tilt/Trim Wiring

This is were I'm confused with this diagram. The top right picture around the solenoid with the what looks like an electrical strip. I don't have all those wires or connectors to the throttle control.

Can I just hook up the solenoid from a separate tilt/trim switch to the solenoid then back to the trim motor.
If so do you have to have 2 for that way or can do it with 1 solenoid, there was a drawing on the forum that has 2 solenoids so I was just checking

Thanks for the reply

Ok after looking at the picture a little more I think I understand it a little better. And i'll try to hook it up the way it looks for the most part. Thanks
 

boobie

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Re: 78 Evinrude 3 Wire Tilt/Trim Wiring

The solenoid is for the up position only ( blue wire). The green wire ( down) comes directly from switch in the control handle. Follow that diagram and you should have no probs.
 

gnt530118

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Re: 78 Evinrude 3 Wire Tilt/Trim Wiring

Ok one more question. I got the new solenoid and was going to hook everything up but don't know which wires go to witch posts on the solenoid. There are the 2 big posts. One small post that has an I and the other small post has an S. I didn't want to guess the wires and do something wrong. Looking at the pictures it looks like one of the small posts are grounded but they have the I or S by them. Which post gets the ground?
 

boobie

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Re: 78 Evinrude 3 Wire Tilt/Trim Wiring

You have an automotive solenoid. Hook the blue wire to the S terminal and nothing to the I terminal. The ground goes back to the mtr block from the base of the solenoid.
 

RRitt

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Re: 78 Evinrude 3 Wire Tilt/Trim Wiring

you could just make life easy and use a more modern relay harness. The entire harness including a pair of relays and a 30A self-resetting circuit breaker is about $30. You take the black trim motor wire and ground it solidly to engine. I usually cut it to 8" and use a copper lug underneath the pump mounting bracket bolt. Then you cut the green and blue wires to 36" and run them into the engine starter bracket. Depending upon relay harness selected they will need to be terminated with either a .25" female spadfe or a 0.18" bullet (aka Ford aka trailer) connector. Good trim relays (2) come with a metal mounting tab and you screw them onto a solid spot near the starter relay. you connect the fused red wire from harness to starter solenoid 12+ input, the two small control wires go back to your console switch, the fat blue wire to motor blue, the fat green wire to motor green, and the fat black wire to engine block. You can have as many switches as you desire. Just wire them all up in parallel. Before connecting the relays you need to make sure they are the four pin N/O variety since you have a 3w motor with common ground. If you have the 5pin type then you need to cut or snap off the center post (# 87a) without damaging the relay.

Generally speaking, relay wiring is better than solenoid or direct. It typically has shorter cables which reduce voltage drop and deliver more power to the trim motor. Additionally, the self resetting breaker prevents the motor meltdown that is unusual but not rare in 3w systems.

Mercury-force-volvo are all standardized generic wiring that will work on any boat and can be found on ebay for dirt cheap. Better for cheaper ... what more could you want?
 

Joe Reeves

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Re: 78 Evinrude 3 Wire Tilt/Trim Wiring

I have a 78 Evinrude 115Hp outboard model 115899C. I cannot find any solenoid box or trim switch anywhere not even on the control box. However I can't find a wiring diagram to do it.

P-TILTWIRING.jpg


There'ya Go!
 

RRitt

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Re: 78 Evinrude 3 Wire Tilt/Trim Wiring

the problem with these 197x wiring schemes is two-fold.
First, you need a big fat trim switch capable of sustaining 20A with as much as 30A peak.
Second, you have long wire runs on a high amp low voltage circuit making the system more expensive and less reliable.

Since he doesn't seem to have any existing wiring or switch I think a modernized wiring scheme would be better. He can run speaker cable from console switch to outbard. He can use any $7 SPDT momentary switch that mounts in any convenient location. Additionally the 30A breaker will protect both his wiring and trim motor.
wire.jpg
 
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