77 johnson 25hp ignition wiring help Please!

[santana21]

Hello all,<br /><br />I have what I believe to be a 1977 Johnson 25 horsepower with remote controls.<br /><br />The model/ serial plate has been removed and I can't find the model number on the welch plug.(plug has no numbers on it whatsoever.<br /><br />I have the Clymer shop manual for 1973-1990.<br /><br />I am trying to wire a new ignition switch into the panel.<br /><br />Panel has the following:<br />Electric choke switch<br />Light that warns of a hot engine<br />Ignition switch off/on/start.<br /><br />The wiring harness has the following:<br />Red<br />White<br />Purple/White<br />2 black<br />Grey<br />Brown.<br /><br />I have deduced the following:<br />Red = battery<br />White = solenoid<br />Purple/White = electric choke<br />Black = ground.<br /><br />I need some help with the wiring on the back of the ign. switch.<br />The switch has the follwing:<br />B for battery<br />A for accesory<br />S for soleniod<br />M for ground<br />M for Magneto Circut<br /><br />the shop manual lists the following wires to the switch:<br />purple<br />white<br />black<br />yellow black<br />yellow<br />(you can see why I am confused)<br /><br />I connected the red to B.<br />White to S and the starter spun when I switched to key to start like it should.<br />I connected the Purple to A and Black to M for ground. I got full battery voltage and the electric choke does what it's supposed to do, momentary on and off.<br /><br />While checking voltage I tested the other black wire and it gave about 1 volt less than full batery voltage. <br /><br />What goes on the magneto circut? Brown , grey or other?<br /><br />What goes on the engine warning light?<br /><br />This motor has a charging system, does any of this have to do with putting current back in the battery? The shop manual says not to wire any type of accessories to this circut. Nothing else is wired to it like lights or horn, they are straight to the battery.<br /><br />Last question. There is a volt meter on the dash. How does it hook up?<br /><br />Thank you in advance for your great help!<br />Jim

 

[OBJ]

Re: 77 johnson 25hp ignition wiring help Please!

Couple questions Jim.....where does the harness plug into the engine at....on the front of the engine (lower pan) or inside the cowl....big plug?<br /><br />The gray wire in the harness is the tach lead from the engine. The wire your calling brown, sure it isn't more of a tan color? That one should go to the overheat light. The other side of of the light goes to the "A" on the ignition switch.<br /><br />Both black wires go to the ignition switch. One black goes to one of the "M"'s on the switch and the other goes to the other "M" on the switch. These black wires kill the engine when the switch is in off.

 

[santana21]

Re: 77 johnson 25hp ignition wiring help Please!

The harness plugs in under the cowl, big plug.<br /><br />The wire is more of a tan color than brown.<br /><br />Which black goes to which M? does it matter?<br /><br />How does the voltmeter hook up?<br /><br />How does the speedometer wire in. It has two small screws on the back plus the pitot tube hookup. I assume power and ground but not sure.<br /><br />Thank you <br /><br />Jim

 

[OBJ]

Re: 77 johnson 25hp ignition wiring help Please!

Your engine is a 77 or later model. 76 on back plugged in to the front of the lower pan.<br /><br />The tan goes to the overheat light.<br /><br />Really doesn't matter which "M" the black wires go to.<br /><br />Voltmeter, runs from the "A" terminal on the ignition switch to the "+" side of the voltmeter. The "-" side runs to ground.<br /><br />Same for the speedometer. Power is just for the illumination light in the gage.

 

[BoatBuoy]

Re: 77 johnson 25hp ignition wiring help Please!

Jim, I have the OMC manual for that '77 25hp and I don't show the wires that you say you have. The wiring diagram shows red/purple, white, purple/white, black/yellow/ and black. Also, that engine has no overheat sensor.<br /><br />red/purple - Bat. terminal<br />white - S terminal<br />purple/white - choke switch then from the other side of the choke switch to the A terminal<br />black/yellow - M terminal<br />black - other M terminal

 

[santana21]

Re: 77 johnson 25hp ignition wiring help Please!

Boatbuoy,<br /><br />You are correct, the manual doesn't show the wires I have. What I am basing the 1977 on is on the carb cover it says on a factory sticker 1977 and gives some 34 degree setting. I don't know what else to go by.<br /><br />I was looking throught the manual and that seemed the closest to what I have because of the choke switch and electric choke.<br /><br />Jim

 

[OBJ]

Re: 77 johnson 25hp ignition wiring help Please!

Possible that the harness you have is not the original. BB is right, no over heat sensor on a 77'.