Keyswitch Wiring

[Solex 27]

It  seems like I have encountered every kind of electrical problem imaginable when putting this tractor back together, but the Magnum 12 starts and runs strong. The issue for today is getting the motor to shut down from the key switch, it continues to run when the switch is in the off position. I have a 103991 switch that is loose and not installed in the metal panel, it is wired as follows:

M terminal - White wire from the Ignition Module
R Terminal - Has two wires going into this terminal, one from the purple wire from the engine, the other from a PTO switch
B Terminal - Red wire from solenoid
G terminal - Black with blue stripe from PTO switch
S Terminal - Black wire to seat switch
A terminal - empty

I may not be 100 correct on the PTO/Seat wiring because it is hard to follow.
So the issue is that the switch is not killing the engine when switched to the off position. The switch is new so it should be good.
 

[rmaynard 14,897]

The body of the switch is where it gets it's ground. It won't kill unless it is mounted to the grounded dash.

[Save Old Iron 1,563]

M terminal - White wire from the Ignition Module
R Terminal - Has two wires going into this terminal, one from the purple wire from the engine, the other from a PTO switch
B Terminal - Red wire from solenoid
G terminal - Black with blue stripe from PTO switch
S Terminal - Black wire to seat switch
A terminal - empty

 

​G terminal - Black with blue stripe from PTO switch

This is one of several incorrect connections. You have either wired the switch incorrectly or have misspoken regarding the wiring. The "S" terminal is for the starter, not the seat!

Remove the PTO ?? wire from "G" and connect the "G" terminal to a good metal ground. This terminal is electrically the same as the metal body of the ignition switch and is used in tractors with plastic dasboards.

[Solex 27]

I did paint all the panels and added a new deal over the keyswitch panel so adding a ground wire to that G terminal sounds like a good idea. The S terminal is going to the starter just to clear that up. The current G terminal wire is going to the Petal Interlock Switch or the Seat Switch, hard to tell. Can It just just keep it wired this way and add a ground wire to this terminal? Do I need to find another home for the 
current G terminal wire?

Edited June 5, 2015 by Solex

[Save Old Iron 1,563]

Remove what you call the "current G wire" from the G terminal. Since the G terminal is connected to the switch body only in the OFF position - and the switch body was connected to nothing (electrically) - the wire connected to G is connected to nothing.

Ground the G terminal and check if the engine shuts down correctly.

I'm sure we will need to do more rewiring - probably in the safety circuits / pto.

Edited June 5, 2015 by Save Old Iron

[Solex 27]

That worked nicely Old Iron, I removed the wire from the G tab on the ignition switch and replaced it with a ground wire that I ran up from frame. The engine will now shuts down by using the key. Many Thanks again, hopefully one day I can contribute to the Forum. Now about that G wire that previously occupied the G terminal on the switch, do I leave it unconnected?

[Save Old Iron 1,563]

 Now about that G wire that previously occupied the G terminal on the switch, do I leave it unconnected?

​We have to trace that wire back to its origin. With the wire disconnected, there must be some function not operating properly.

[Solex 27]

Thanks again Old Iron for all the help, since the tractor runs, I am going to take a break from the electrical and assemble the rest of it. After that Is complete I will find out what is not working and open up another electrical thread.

[wrightorchid 261]

similar issue.  I had replaced the switch, and fixed the electrical connections.  Now it won't shut off in the Stop setting, and the volt meter and hour meter have stopped.   312-8 M12.  Not sure what has changed since last week, when it was running fine.  It ran OK for about 2 months.  no fun chasing electrical gremlins....

[Don1977 604]

similar issue.  I had replaced the switch, and fixed the electrical connections.  Now it won't shut off in the Stop setting, and the volt meter and hour meter have stopped.   312-8 M12.  Not sure what has changed since last week, when it was running fine.  It ran OK for about 2 months.  no fun chasing electrical gremlins....

Does it start right up on the first try or do you have to try it a couple of times before it turn over like it should. Mine 312 has been a little hard to get it to turn over for a while.
I tried to start it a few weeks ago, turned the switch and nothing, tried to jump it still nothing. Was look around and found the dash screws loose. Tighten them up and it started. They were just a little rusted clean them on a wire wheel ,sanded the dash panel under the screws, now it starts right up.  Now my other Wheel Horse act like the battery is dead, haven't  had time to check it out.

[wrightorchid 261]

It starts fine, just won't shut off.  I have to throttle down, and then pull the choke.  I have another ignition switch, but this one on it is only a few months old.  I'll have to check all of the connections, and grounds.

[Save Old Iron 1,563]

Set your multimeter on ohms (lowest range if the meter isn't auto ranging). Connect the black probe to battery NEGATIVE.   Touch the red probe to the exposed metal of the ignition switch body (where ignition key is inserted). The meter should show a direct short. If not, touch the red probe to a non-painted area on the metal hood stand that holds the ignition switch

There should be continuity of the battery negative to the hood stand and continuity of the hood stand with the metal body of the ignition switch.


 

[wrightorchid 261]

Thanks, will check later.  Not sure what has changed since it was working, and the ignition switch body is still tightly mounted.