Add tilt/trim to manual outboard

[ltj211]

Hello, I recently purchased a 1973 sportcraft17' runabout with a '78 Johnson 115hp outboard. The motor is a manual tilt (from what I have found, this is the factory set up with an ML designation). I found a 3 wire tilt/trim assembly on ebay and I want to find out if this unit could be added to the ML motor easily with an aftermarket tilt/trim switch. Ive done some research to figure out wiring as far as actually hooking up the unit, but wasn't sure about hookinh it to a manual tilt motor. Any help would be greatly appreciated.

 

[boobie]

Re: Add tilt/trim to manual outboard

If you can find a complete tilt/trim unit for a good price go for it. If not check out CMC.com for an after market.

 

[ltj211]

Re: Add tilt/trim to manual outboard

So the unit got here last night. I bench tested and it works great (just a little dirty). I tried to find a solenoid junction box on ebay but the only things I found were the newer relay boxes. All the exploded view diagrams I have found (BRP, Evinrude, etc.) show half of the parts for box as obsolete and unavailable. I have seen the wiring diagram on the forums before and wanted to know if I could just build my own box based on that diagram, or if I could buy one of the 2-wire relay harnesses and make it work properly based on that. The unit has the three wires from the motor with ring terminals (look to be about 10ga) and the two wires for the sending unit (honestly looks like some lamp cord), also with ring terminals. Thanks again.

 

[boobie]

Re: Add tilt/trim to manual outboard

If it was my motor I'd build a box after the original design. Much more simpler. You can find wiring diagrams for it on here.

 

[Slojoe]

Re: Add tilt/trim to manual outboard

I believe 78 is the first year for the internal tilt/trim assembly where the lift assembly fits inside the transom bracket. 77-down had the pump and/or cylinders mounted on the side. I'm not 100% sure on that as things changed from 77-79 as far as the stern bracket, some models used a hybrid with the lift inside and the pump outside. Just make sure you have the proper assembly to fit your outboard, pics would help.

As for the wiring, the 3-wire system should be the simpler one to rig from scratch with no relays as I recall. Starting at the lift motor, there should be a harness from 3 to 6' long, that will get the wires inside the boat to the battery. Blue, green, black wires as I recall, although the black may be red. Then a plastic OMC plug at the end. There should be a single wire coming out of the plug or possibly 2. This wire(s) will go to the battery for power. The positive one should be connected to a fuse.

Then there will be a separate OMC switch, either in your shifter handle or on a plate with 2 holes to bolt to the dash. If you look at ebay item 120849328916 you will see a pic of the plate I mean. That uses a regular 3-position toggle switch, with center being "off." Up and down are spring return to center. Then the OMC harness plugs onto the rear of the toggle, with 10-18' of wire running to the stern, the end of the harness has a plug that connects to the harness going to the motor.

If you are missing the OMC harness it is easy to install wires one at a time, standard spade connectors will connect to the toggle switch or any factory plugs that you may have. Individual wires should be run through a plastic flex tube, can usually buy a roll at napa or ebay.

The 2-wire tilt/trim motor is a different beast entirely and requires relays and a junction box, either inside the boat or else under the cowling on later models. A 3-wire system shouldn't require any relays as I recall, as I said above, much easier to wire from scratch. It's been a few years since I've dealt with a 3-wire system but the OMC harness is really nice and makes for an easy installation with the quick attach plugs, if you can find one.

Re-reading your post: It sounds like your wiring harness has been altered, if you can post up some pics maybe we can help figure out what you have and where to go. Lamp cord is not a good idea on a boat.

 

[ltj211]

Re: Add tilt/trim to manual outboard

Thanks for the replies guys. Boobie, I was thinking that building my own junction box would be easiest, and just set it up as it would have been from the factory. I guess my questions for that would be is a solenoid set up the same as a relay set up in the sense that you only need a smaller gauge wire from switch to solenoid? And also, would the TH Marine universal trim switch sold on iBoats work?

Slojoe, it is the style where everything is between the transom brackets (and it came with brackets attached). The boat was never set up for power trim, so everything will have to be wired from scratch. I'll get some pics tomorrow to better explain, but the actual trim unit is off an early 80s (same hardware set up as the 78). And I agree about the lamp cord, but the wiring is kind of dirty, so it may actually be some marine 16/2, that is if that's even something that was available.

Thanks again.

 

[Slojoe]

Re: Add tilt/trim to manual outboard

If everything is fresh water you should be able to replace the brackets. If anything is salt water used, I'd make sure you can get things apart before investing too much time.

On the wiring, I've installed a couple factory, OMC, 3-wire, tilt systems over the years. They were complete factory harness from switch to outboard with no solenoids or relays. But they were just power tilt from the early 70's, no trim. Maybe when they went to power trim they required a solenoid b/c of extra heat generated?

I prefer simple wiring and no junction boxes if possible. I.e. no solenoids, relays, etc. But if you need the solenoids for safety I guess there is no way around it. The old motors went up and down real fast but the newer units with trim at the end of the cycle require a lot of time and current through the system. I'm guessing it is the trim that requires a solenoid to keep heat off the wires...?

We've reached the extent of my knowledge here and i'll quit posting on your thread so that more knowledgeable members can help you get it figured out. good luck-

 

[RRitt]

Re: Add tilt/trim to manual outboard

So the unit got here last night. I bench tested and it works great (just a little dirty). I tried to find a solenoid junction box on ebay but the only things I found were the newer relay boxes. All the exploded view diagrams I have found (BRP, Evinrude, etc.) show half of the parts for box as obsolete and unavailable. I have seen the wiring diagram on the forums before and wanted to know if I could just build my own box based on that diagram, or if I could buy one of the 2-wire relay harnesses and make it work properly based on that. The unit has the three wires from the motor with ring terminals (look to be about 10ga) and the two wires for the sending unit (honestly looks like some lamp cord), also with ring terminals. Thanks again.

run 12v through a 5A fuse to center position of trim switch.
run two 18-20awg wires from switch back to engine.
buy a $30 ebay generic trim harness such as -
Wiring Harness Converts 3 Wire Tilt Trim Motor to 2 Wire 50 Amp Fuse 2 Relays | eBay
- or -
84-826802A12 | HARNESS ASSY-TRIM | Mercury | Crowley Marine


heavy black goes to engine block, heavy red goes to starter batt connection
Switch up/down goes to light gauge bue/green wires
Trim motor up/down goes to heavy gauge blue/green wires.
mount relay tabs onto starter bracket and secure wires away from harm

for 2w trim motors:
use relays as shipped
run a SS galvanic bonding strap from aluminum pump to a nearby anode
CABLE ASSY (#88238A18) | Performance Product Technologies


for 3w trim motors:
break off relay center tab #87a (creating a 4 pin N.O. relay)
secure trim motor black wire to engine ground
no galvanic bonding strap is required for 3w trim motors


for all trim motors:
make sure that the trim wiring has an inline fuse between relays and battery post. if not, splice in a 25-30A ATC holder & fuse. A holder is preferable to plain utah plugs found on the chinese harness. It will isolate the fuse from vibration and moisture helping to create a more reliable wiring system. 10 Gauge ATC in Line Fuse Holder Electric Fan Shaved Door Popper Air Horn Kit | eBay

 

[ltj211]

Re: Add tilt/trim to manual outboard

OK,the solenoid came in, and I picked up a terminal strip and box. I want to start building the junction box based on this diagram

This is the unit
The motor wiring
and the sending unit wiring

and this is the solenoid I got (per crowley, brp, etc. exploded diagrams)

My only real questions at this point are does anybody know what AWG wire to use between the various connections (8awg from bat. to solenoid, 16awg from switch to solenoid, etc.), what are the ring terminals from the sending unit that are not connected to anything in the diagram, and does it matter which terminal on the solenoid is pos. vs. neg., or does it not matter. The solenoid has the two smaller posts labeled with S and I.

Thanks for all the help so far, hopefully I can finish this section of the project and move on to the next.