Logo
FULL SITE MENU

1978 Johnson 25EL78C Wiring Help @ Bow/Dashboard/Key Switch Panel/Ignition End

L

LooseGoose

New member
Need help wiring an ignition switch and creating whatever extra switches/guages needed to properly and safely operate a 1978 Johnson 25hp 25EL78C on a pontoon, remotely; specifically need help knowing where the wires go that come from the harness that goes from the motor to the front/dashboard area. At the motor end is a red rubber plug end that connects to a Black rubber plug end that goes to the harness for the motor wiring. My 'red end harness' has the red rubber connection on one end...and the following loose wires on the other end, which are my challenge: RED - WHITE - BLACK - BLACK w/YELLOW STRIPE - PURPLE - PURPLE w/WHITE STRIPE - BROWN - GRAY (which seems to be folded and taped closed as if it has not been used.) I don't have a dashboard...or a key switch panel...I have to figure out what I need to build...I guess. I already have a seperate control box that is off-brand, which controls the throttle and shift cables only...so I guss I'm okay in that department and don't need a control box...I guess. (although I do wonder if the perfect solution for my harness is such a control box. Anyway, as I play with the wires, I get the following: 1. Shocked (lol) not knowing where everything goes. 2. I can start the motor and it stays running, by turning the key and with the red and white connected only...although it does not turn off when I turn the key to OFF...(and I sure would like it it...if it can somehow). 3. If with motor running, I connect the BLACK w/YELLOW STRIPE to a ground, it kills the motor (seems like a way-to-manual way to cut the motor...isn't that what turning the key to OFF should do?) 4. If I touch the PURPLE w/WHITE STRIPE wire to power, it activates the CHOKE...but I know not where the wire is to be connected. 5. And I'm lost on the PURPLE, BROWN AND GRAY. 6. I read that TAN (which I don't think I have...looks BROWN TO ME, but I could be wrong, could go to an ALARM HORN (which I do not have, nor know how to wire), or WARNING LIGHT OF SOME KIND (TEMP, ASSUME -again, do not have such a light.) Any help would be greatly appreciated!
 
Last edited:
Since my post I have one more note: the ignition switch I have is apparently from a CAR or TRUCK, so I just ordered the switch that goes with my motor. By the way, I would gladly PAY for assistance, even. I see there are tens of thousands of posts...many of which never get attention with responses and many with responses years later. I don't have that much time. I have like a week to figure this out, so anything at all in the way of accurate help would be appreciated.
 
I suspect that the reason you're not receiving any advice is that you're mixing parts that cannot be mixed... such as a RED electrical plug being matched up with a BLACK electrical plug. The wires within the two wiring harnesses do not match up.

However, if all you want to know is what wires attach to what terminals of the marine ignition switch, they are as follows:

You state that you have wires as follows: RED - WHITE - BLACK - BLACK w/YELLOW STRIPE - PURPLE - PURPLE w/WHITE STRIPE - BROWN - GRAY

Gray = leads to the "S" terminal of a tachometer (Do Not attach to the ignition switch).
Purple/White = Attaches to the "C" (choke) terminal of the ignition switch.
Purple = Attaches to the "A" (accessory) terminal of the ignition switch.
Black/Yellow = Attaches to the raised "M" (magneto) terminal of the ignition switch.
Black = Attaches to the other plain "M" (magneto) terminal of the ignition switch.
White = Attaches to the "S" (solenoid) terminal of the ignition switch.
Red = Attaches to the "B" (battery) terminal of the ignition switch.

Brown ?? If this is a heavy duty gauge wire, it would pertain to a generator amp meter, BUT if it is the same gauge as the other wires (excepting the RED wire), it would be the sensor lead for the warning horn. A wire would lead from the "A" terminal of the ignition switch to one of the horn terminals, then the TAN wire would attach to the remaining terminal of the horn.

Giving advice on a engine that is equipped with the required items is one thing. It is nest to impossible to give advice when the wrong items are being installed. However, I hope this bit of info (above) is helpful to you.
 
Thank you for your thoughtful reply. I am focused now on the harness I have and would like to know, if it is a fact that the harness with a RED rubber plug end does NOT go with the engine wiring harness that has a BLACK end, do you have any idea what such a RED end harness goes to, given the combination of wires it has...and just to be sure, do you know for a fact that I should be seeking a BLACK end - type harness of some sort, to go with my 25EL78C? By the way, that BROWN could be TAN, as it appears to be the same guage as all except the RED. Thank you again!
 
Red plug harness on motor will not work with a black plug on control box end.----You will need wiring diagrams to make something up.-------------Is there a shift cable and a throttle cable in the black plug control ??------Used red plug controls are easy to find.
 
LooseGoose said:
1 - I am focused now on the harness I have.
2 - Is it a fact that the harness with a RED rubber plug end does NOT go with a BLACK end engine wiring harness?
3 - Do you have any idea what such a RED end harness goes to?
4 - Do you think that I should be seeking a BLACK plug type harness to go with my 25EL78C?
Click to expand...

To make sure that we are on the right page here... I read your post to say that you are saying that the BLACK plug wiring harness is on the engine? I may be in error but I am under the opinion (depending on my memory) that the black plug harnesses were only used from 1968 to 1972... and that your 1978 engine should have the RED plug wiring harness.

Perhaps another member will jump in here to clarify that thought one way or the other.

1 - That is the best line of thought to be having.

2 - Absolutely... To attach the RED plug to a BLACK plug, then install a battery into the circuit would have disastrous results (voltages leading to wrong areas, etc).

3 - The RED plug harness setup connects to any other Evinrude/Johnson engine that has the RED plug setup regardless of its horsepower, starting in 1973. If you could find a RED plug wiring harness that installs on your engine, that would be the way to go.

4 - That would be the easiest route to take IF that existing BLACK plug is wired correctly to your engine.

NOTE: Send me a PM with your email address and I'll send you the wiring harness page from the OMC parts manual which may come in handy... Remind me of why you're writing.
 
Last edited:
Thanks racerone,

I meant...this situation is...one in which I have a MOTOR that has a BLACK plug harness on it...and I do not intend to replace that harness...I willleave that BLACL end harness that is on the motore, on the motor. My challenge is that with that BLACK plug end harness that is on the motor NOW, I then have a RED-plug -ended harness that goes to nowhere for now. So I guess at this point I am going to check out joereeves comment next. Thank you though! Every bit helps!!
 
Thanks joereeves, Yes I do have a BLACK plug harness on the motor. From what I can tell, it looks like it has been there for a long time. The RED plug end is attached to the harness that would lead to the bow area... If it helps, I can share that it's a 1993 pontoon that used to have a different outboard that must have used a tiller...AND I have no way of knowing if this Johnson 25hp 25EL78C came WITH the RED plug harness or not. But I do know that the ignition swith I inherited with this setup is for a CAR. So I have ordered the OEM key switch assy and I have that coming soon. I have no idea what it will look like when I get it...and I sure hope it comes with instructions. I guess my main problem is I have little to go on, regarding my mysterious RED plug harness...for which I am still in the position of questioning if my BLACK plug harness that is on my motor, is even supposed to be there. It sure seems like it's been there a while. I'd suspect the RED plug harness, if anything...but what is strange is that the power seems to flow through okay. I can't tell for sure, but please see my original post in which I share what happens when my RED plug harness, is plugged into my BLACK blug engine harness. It seems to work...then again I was messing with the AUTO ignition when I wrote that...but there are similarities. Thank you again!!
 
It's hard for me to read long paragraphs so perhaps I am missing something. I'll take a wild guess that you have come across this rig recently and that the engine has been running in the past with that RED/BLACK plug combination. If this is the case, I would assume that the wiring has been adjusted if needed and that all is well in electric land.

Which brings me to the question of the wiring to an ignition switch. The new marine ignition switch should have six (6) terminals with a push in key function that supplies voltage to the choke solenoid. In which case the wires you mentioned would connect as I mentioned previously and re-listed here.

Gray = leads to the "S" terminal of a tachometer (Do Not attach to the ignition switch).
Purple/White = Attaches to the "C" (choke) terminal of the ignition switch.
Purple = Attaches to the "A" (accessory) terminal of the ignition switch.
Black/Yellow = Attaches to the raised "M" (magneto) terminal of the ignition switch.
Black = Attaches to the other plain "M" (magneto) terminal of the ignition switch.
White = Attaches to the "S" (solenoid) terminal of the ignition switch.
Red = Attaches to the "B" (battery) terminal of the ignition switch.

Tan = Do NOT attach to the ignition switch. A wire would lead from the "A" terminal of the ignition switch to one of the horn terminals, then the TAN wire would attach to the remaining terminal of the horn.

NOTE: TAN WIRE... If using a old style metal horn that has but 2 slide on terminals, it makes no difference which terminal the wire slides on, BUT if a later style plastic "self warning" horn that has a build in black ground wire... a horn that beeps when you turn the key on, the TAN wire must be attached to the slide on terminal closest to that ground wire.

 
I'll try to keep it short...sorry. I still don't know what the 25EL78C was built to have, from the factory, as a Johnson product:
Was it built to have a black plug end wiring harness, that then goes into a red plug end harness, that has wires like I have?
NOTE: I have no reason to believe these parts have ever been working together...nor reason to believe that they have.
 
Last edited:
Back
Top