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68 20hp Johnson Wiring Diagram

The John

The John

New member
HI everyone,
I have a 68 20hp Johnson outboard that has been sitting for a while (model# FDL-22M). This outboard has electronic start, and currently the motor is in its forward gear (which I believe to be the default before positive ground came about). The problem is I haven't been able to find a wiring diagram to be able to test this outboard. Would anyone happen to have or point me to a wiring diagram for the ignition? I have ordered a manual but I am not sure that this information will be included in that book.


I am not new to boating or outboards but I normally run regular pull start outboards on my boat. This outboard is a replacement for another which gave up on life after 30 years of hard service.


In the meantime I have ordered a new impeller kit, and a tune up kit with new wires and etc. I will change the fluid in the lower unit when the balance of the parts arrive.

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"Fish, I love you and respect you very much. But I will kill you before this day ends"
-Ernest Hemingway, "The Old Man and the Sea"
 
The 1968 20hp Johnson has a mechanic shift setup... there is no default.

Positive ground ??

The ignition system is strictly magneto.

The starting system could be electric... there is no such thing as electronic start. I will look to see if I might have a wiring diagram as I'm sure other members will also.

Are you saying that you do not have the wiring harness that leads from the engine to the dash (control area) and you need to build that harness?
 
Good morning,
Positive Ground- I read the motors of this vintage with electronic ignition have a positive ground over the much safer negative ground (https://www.reference.com/vehicles/positive-ground-system-work-28165973cecd8bc8)

I have the basic harness from the outboard to the ignition, but I want to be certain that I wire this up correctly from the battery (not sure if any special connections are necessary, this is my first electronic ignition outboard).
 
The John said:
Good morning,
Positive Ground- I read the motors of this vintage with electronic ignition have a positive ground over the much safer negative ground (https://www.reference.com/vehicles/positive-ground-system-work-28165973cecd8bc8)

I have the basic harness from the outboard to the ignition, but I want to be certain that I wire this up correctly from the battery (not sure if any special connections are necessary, this is my first electronic ignition outboard).
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You sir are missing my point completely! This 1968 20hp Johnson DOES NOT have electronic ignition, NOR does it have a default shift position, NOR does it have a "Positive" grounding setup!

Moving ahead with what you apparently have planned of throwing 12v to any other portion of that engine excepting the starter solenoid ) if it exists will result in unneeded expenses!.

I'm aware of the positive ground system that existed back in the early days of the Ford Motor Company and remember working on a few of them myself back then, but that became a thing of the past some 75 or 80 years ago.

I have no idea what you're reading but you are being led astray.
 
Good morning,
I may have been lead astray which is why I thought I would post here as I dont know much about Outboards.

in regard to the comment on electronic ignition, you are incorrect. Otherwise the long cables connected to the starter inside the outboard would say differently. I think we are talking about two different things, I am talking about the positive/negative wire that attaches to an ignition switch to start the motor. My outboard has points so the spark is not created through an electric distributor.
 
The John----Stop now-------Time to start listening to folks who have worked on these motors since it was new.------It is electric start.-----No such thing as default to forward on a 20 hp model.-----Standard points , coils and condenser ignition magneto.-----Does not require battery to run.------And no there never was " positive ground " on one of these motors.
 
Wrong motor, but close enough. There weren't many changes in those years.
 

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BTW, Joe, racer, and I probably have around 150 years of combined experience. Believe it when we say your motor has an OMC universal Magneto. It can be rope started and run with no external electrical connections whatsoever.
 
The John said:
Good morning,
I may have been lead astray which is why I thought I would post here as I dont know much about Outboards.

in regard to the comment on electronic ignition, you are incorrect. Otherwise the long cables connected to the starter inside the outboard would say differently. I think we are talking about two different things, I am talking about the positive/negative wire that attaches to an ignition switch to start the motor. My outboard has points so the spark is not created through an electric distributor.
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Really wish you hadn't said that!

Red Foreman, I suspect, is looking for you!
 
The John said:
HA, I am sure, which is why I came here for some better information. :)
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Gentlemen, please excuse my ignorance. I have one of these and I’m trying to piece together the chewed through and flea circus wiring that I was left with. Can you please tell me what the "black” ‘M’ stands for on the switch diagram please? The ones that are connected to the engine armature? In my boat I have no spark, everything else matches up to your schematic, but the armature wires were left attached to a single wire that is just lying on the deck. I have no spark, even when I pull start the engine. I do however have 12v positive power to the solenoid, and the switch does engage the starter when turned on. The installed switch only has 3 wires coming in or out of it. 12v from battery, 12v send (when key is in run position) and 12v momentary (when it is twisted to the start position).

any help would be appreciated. Thank you again

Chris
 
The black "M" wires are the kill wires. They stop the engine when the key is turned to the "OFF" position The key switch does that by electrically connecting the two wires together, thus shorting out the magneto. The engine should run if the two wires are completely disconnected,
 
The " M " is magneto.----On the switch the M terminals are open for motor to run.----closed for motor to stop.------Under no circumstances should you apply 12 volts to M terminals.----Pull the flywheel to inspect magneto coils.
 
racerone said:
The " M " is magneto.----On the switch the M terminals are open for motor to run.----closed for motor to stop.------Under no circumstances should you apply 12 volts to M terminals.----Pull the flywheel to inspect magneto coils.
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Oh my gosh! Thank you very very much! That was exactly what I was going to try. I'll try and see if I can find a proper replacement switch, since this looks like a aftermarket generic one. That could have cooked things. Thank you again for your knowledge and response!

Have a great weekend, and be safe.

Chris
 
Upon further inspection, I've noticed that the black magneto wires coming from under the flywheel have a new crimped on butt connector that has the two black magneto wires from under the flywheel twisted to gather and crimped on one end of the connector and the other end of the crimped connector has the long wire that was lying on the deck. So if I understand you both correctly, the previous owner or repairman has crimped the magneto ends together effectively killing the engine, so it never would have ran in it's current configuration?
 
Disconnected those two black magneto cables and she started up second pull! You guys are amazing! Thanks for all of your guidance and taking the time to answer my questions. Have a great week!
 
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