[nitrosport_5]

Ive got an early i believe John Deere 140. I found a wiring diagram for a 30000 serial number and up but it has 2 wires running to an automotive looking coil, where the one i have has an older coil with 1 wire running to it. I would go get the serial number but its late and its out in the shop...

Ive got no power to the coil when i turn the key on, but when i crank the engine i do get power pulsing to that wire. Would that suggest a bad coil? or should the coil have more constant power.

 

[woodpecker41]

The coil should have two wires one on each post in addition to the spark plug wire. Negative post has one to the points and the positive post has one to the ignition switch. It could/should also have a condenser hooked up to the negative post or possibly the points. The pulsing means the points are working. Welcome to WFM. Roger

 

[tommyhawk]

First, welcome to WFM, Matt!
Since I have no idea what the old Kohler Solid State Ignition or magneto ignition looks like, I should probably not be posting. However, if it's possible that the one wire coil is something of that nature, and it saves Matt from more problems, I don't mind showing my ignorance.

Having only one wire on a coil and getting some pulsing voltage is difficult to understand from a conventional old style automotive coil. Perhaps you can give us more info such as the serial number on the tractor or the spec. number on the engine. Is it a 12HP (K301) or 14HP (K321) engine? Does the engine have breaker points?
Could you post any pictures or e-mail them to Roger, me, or another member to post for you. Might be something interesting to see.
JD Parts is not available for me at the moment. Maybe I can take a look later.

tommyhawk

 

[rick]

Does your 140 have the breakerless type ignition system? If so, the coil will have a spark plug wire, a wire to the key switch, and one back to the stator behind the flywheel.

 

[nitrosport_5]

016785m is the tractor serial number. Can't see one on the block. Not sure what type of ignition it has. Haven't dug too deep. Here is a pic of the coil. Sorry, forum made me make the pic aweful small.

 

[cd202]

That's the beakerless solid state ignition not the coil ignition

 

[rick]

It looks like your wiring has broken off the coil. Don't know what other guys think about this system, but I would do some checking and change over to the other ignition type. That serial # I think makes it 69 model.

 

[cd202]

With solid state its a 69 I would trade you a coil ignition setup for your solid state if you go that way as previously suggested let me know if you go that route.

 

[nitrosport_5]

Yeah the wire broke off. I fixed it after the photo. I just went out there half our ago. Had spark ran great. Let it sit. Just now tried to start. No spark nothing. Rattled the wires checked plugs nothing. So this ignition setup is known to cause problems?

 

[cd202]

Most have been converted

 

[nitrosport_5]

Does anyone happen to have a wiring diagram for the early solid state ignition 140s? I almost want to say it is the kill switch that could possibly be bad. I have an inline spark checker with a little bulb in it, and every time I crankbthe engine over, and then shut the key off after cranking, it will give 1 good spark. This normal?

If I were to switch to the other ignition type, what all does that involve wiring wise? Thank you for your help!

 

[inspired_metal]

Hi Matt
Welcome, I'm going to suggest a bad key switch or that it is the wrong key switch. When I've had the same problem as you described it was the key wired wrong for the tractor.

 

[KB]

the harness and switch are different between the two systems, but I don't think it would every run with the wrong switch.

 

[nitrosport_5]

What wire is the kill wire? And I assume it is grounded to kill? Or is it a hot ignition wire? I was going to bypass the key switch to see if I've got spark. If I do I know thy is my problem. Not looking to disable any safety devices, just troubleshooting

 

[nitrosport_5]

So I have the ignition switch out. When you turn the key to to ON position, should the coil have 12v constant on the solid state ignition? When cranking or key on, I have no spark or constant 12v at the coil. If I put my testlight on the coil wire it will pulse while cranking. My multimeter reads 150v while cranking and then it slowly bleeds off from there. But that cant be correct or elae kt would blow up the test light. Everything I see leads me to a bad coil or ignition switch. Just CNT figure out if I'm supposed to have 12v constant or not. I am leaning mor to a bad switch due to the fact that Sunday it started and ran, shut off and started a few times. After sitting a bit it did not run.

 

[KB]

you do not need 12V at the coil.

I was test running a 69 I picked up by setting the key to on, and jumping it with my truck, black cable to a head bolt, red cable directly to the starter.

a new ignition switch should be in the 10-20 dollar range at the dealer if you want to throw one at it, I no longer have that tractor to do any further testing for you

 

[nitrosport_5]

I wish I could find a wiring diagram for this year. Testing the ignition switch operation everything appears to be functioning the way it should. Now when cranking and shut key off I get one spark. So I grabbed a test lead and hooked it to the coil wire. While cranking every time I grounded the wire I got a spark. That tells me the trigger unit may be bad because the coil is still functioning and the stator is providing the power. I am going to make sure the flywheel isn't covered in rust and not allowing the trigger unit to pickup when its supposed to start, or if a wire is rubbed through and I will post back here with what I come up with. Thanks for the help everyone.

 

[rick]

Matt, I'll send you a copy tomorrow of the diagram. I suggest you find yourself a service manual for this tractor. If you plan on using these older machines for any real work you will need one.

 

[nitrosport_5]

To be honest, it is not my machine but a neighbor here is town. It has seen quite a few hours of work by the looks of it. Found the wires to the trigger unit had the coating chewed off of then. Repairing them and going to see were that gets me. Thanks again for the diagram. All I have been able to find is the 30,000 and up diagram

 

[nitrosport_5]

I'm just highly confused. Cleaned off the pickup on the flywheel, ran a new lead from trigger unit to coil, and tractor fired right up. Shut it off, let sit a minute, fired right back up. Let itnsit 10 minutes and now no spark again. It is not the ignition switch as I have the coil wired directly to the trigger unit for testing. I am still getting pulsed power to the coil.. Everything checks out including the coil resistance tests.