Electrical Issue? I’m out of ideas....

[BrianSki]

Just to clarify, this is NOT a points machine. I happen to have a 31R977 on my bench and with the coil removed, the resistance from the kill terminal to the laminations is 1.6 ohms(using a Fluke 87-V) as suggested earlier. I'm guessing Aimme that when you measured from the kill tab on the magneto, to ground, with the kill wire removed, you interpreted the very low reading as the tab being grounded.
.......

Finally finally, Rivets, you asked early on for the vin #. Do you have access to the schematic and if so, can you post here?

Telisis.... Thanks for the points info... pretty much all the mowers I worked on have either points or some kind of electronic ignition for the timing. Is this built into the coil?? It does not look like it has wires for electronic ignition.

Yes a schematic would be great. I tried looking one up and could not come up with anything very close.

It looks like grounding the coil kills the spark. So jumpering the switches would kill the coil. The switches need to be open to keep the coil firing. Except for the few switches that have closed circuits for the start circuit.

 

[bertsmobile1]

I see where you are confusing everything
You are measuring the primary resistance but probing from the kill tab to the laminations .
THIS CAN NOT BE DONE ON MAGNETOS WITH INBUILT TIMING CHIPS ( yes I am yelling )
Between that terminal & the coil windings is the hall effect trigger chip and the very act of measuring the resistance through it can fry the chip.
Now I know You tube is full of walking talking dildos who "show" equally mentally challenged how to "test" their coils but it is meaningless and if you un the probes wrong way round destructive .
All that is important is the wire that attaches to that terminal is either open circuit or ground and never ever shows any voltage.
The chip reads microvolts and a few milli volts from the 9V battery in most multimeters can fry it.
Even worse is most are very polarity sensitive and must be checked ( where appropriate ) with the red probe on the laminations & the black on the terminal


The only exception to this are the ones where the chip is remote to the coil so the coil is just that, a coil & most Kawasaki's where their chip is reverse polarity protected and normally closed .

As such the only tests to be done to magnetos is to remove the kill wire & check for a spark when the engine is cranked.
If none is found the magneto is fault
You can check the secondary resistance from the plug terminal to the laminations but as a lot of them have non replaceable HT leads it is a moot point so all you need to do is give the cap a tug, or replace it just in case .

 

[AimmeAshley]

I go back to what was said in post # 4
Make up some short jumpers with a male spade on each end and jump the plugs according to how the switches would connect them
Do this one at a time thus you have bypassed the switch(s) till the problem resolves.
If this does not resolve the problem then there is a short or open circuit in the actual loom .
Armed with a circuit diagram start bypassing sections of the loom with longer wires, these will need a male on one end & a female on the other.
It is fairly common for a wire to fatigue at the crimp so depending on things like temperature or vibrations will make or break contact

Thanks for your response. I plan on making some jumpers this weekend and trying your suggestion.

 

[AimmeAshley]

Ok, just went over this... With the ignition switch ON, the kill wire reads 9.89K. Is that with it disconnected from the coil?? If so, disconnect your safeties one at a time until it goes to an infinity reading. Something is pulling it to ground. You may even try to unplug the key switch too, to make sure that would not be the problem.

Not to confuse you more... I am trying to find where the points hook up to the coil. Maybe through the kill wire. That may be giving you the reading. But then it would not run disconnected. Sometimes easier to see in person. (or it may have some hybrid ignition??)

That is with the coil wire disconnected from the ignition coil.

The only thing that seems to be pulling the kill wire to ground right now is the ignition coil itself. I’ll have to remove the starter motor this weekend to double check that there’s no kink where the kill wire is mounted.

 

[AimmeAshley]

Just to clarify, this is NOT a points machine. I happen to have a 31R977 on my bench and with the coil removed, the resistance from the kill terminal to the laminations is 1.6 ohms(using a Fluke 87-V) as suggested earlier. I'm guessing Aimme that when you measured from the kill tab on the magneto, to ground, with the kill wire removed, you interpreted the very low reading as the tab being grounded.

I also want to confirm that the RIO switch(not the RIS on the dash) is in the tranny, and you can check it by measuring across the two nubs and verifying it only shorts out when switched into reverse.

As lemerick suggested, does the blade lever make good physical contact with the switch when the blades are not engaged? On my JD D105, there is a spring on that lever to make sure it pulls in the switch button when you disengage the blades. Is that spring there? Does it appear to be pulling in the switch appropriately?

Finally, the value you measured of 9.89K ohms is suspect. I'd like you to repeat that test(disconnected kill wire, resistance between kill wire and ground), but with the positive battery lead disconnected(so it won't start). That way you can share the value in all 4 ign switch positions(off, run w lights, run, start)

Finally finally, Rivets, you asked early on for the vin #. Do you have access to the schematic and if so, can you post here?

Yes, with the kill wire detached, I measured from ground to the ignition coil’s kill tab. I re-did the measurement and it is currently measuring 0.3-0.4 ohms.

This is with the ignition switch on the run position.

I also just measured the RIO switch in the transmission (two nubs). I switched it to reverse, and it is showing low resistance. Switching it back neutral or any of gears makes it an open load. I think it’s working correctly.

The blade lever for the PTO is making good contact on the PTO switch. The spring is also looking pretty good as well. I disconnected the wire harness on that switch and made sure that it’s operating correctly.

With the +12V disconnected, and measuring from the disconnected kill wire to ground, I’m getting:

Ignition Switch OFF: 0.4 ohms
Ignition Switch Run w/lights: 9.32Kohms
Ignition Switch Run: 9.34Kohms
Ignition Switch Start: 9.33Kohms

I also have a digital copy of the schematic. Not sure if I’m allowed to post it.

 

[AimmeAshley]

I see where you are confusing everything
You are measuring the primary resistance but probing from the kill tab to the laminations .
THIS CAN NOT BE DONE ON MAGNETOS WITH INBUILT TIMING CHIPS ( yes I am yelling )
Between that terminal & the coil windings is the hall effect trigger chip and the very act of measuring the resistance through it can fry the chip.
Now I know You tube is full of walking talking dildos who "show" equally mentally challenged how to "test" their coils but it is meaningless and if you un the probes wrong way round destructive .
All that is important is the wire that attaches to that terminal is either open circuit or ground and never ever shows any voltage.
The chip reads microvolts and a few milli volts from the 9V battery in most multimeters can fry it.
Even worse is most are very polarity sensitive and must be checked ( where appropriate ) with the red probe on the laminations & the black on the terminal


The only exception to this are the ones where the chip is remote to the coil so the coil is just that, a coil & most Kawasaki's where their chip is reverse polarity protected and normally closed .

As such the only tests to be done to magnetos is to remove the kill wire & check for a spark when the engine is cranked.
If none is found the magneto is fault
You can check the secondary resistance from the plug terminal to the laminations but as a lot of them have non replaceable HT leads it is a moot point so all you need to do is give the cap a tug, or replace it just in case .

Thanks for your response.

I’m aware that these are solid state magnetos/ignition coils.

I don’t think this is an ignition coil issue. Like I said, with the kill wire detached from the ignition coil, the mower will start up.

What doesn’t make sense to me is why the kill tab shows that it’s shorted to ground as soon as I bolt it on without the kill wire attached. That’s what I’m having a hard time wrapping around my head.

I’ll look into using jumpers and checking behind the starter motor in the next couple of days!

 

[bertsmobile1]

SO toss that multimeter back into the tool cupboard
Do as was suggested way way back in post # 5
Make up some shot jumpers ( patch cords actually ) with a male spade terminal ( Yanks seem to call the forks for some unknown reason ) so they plug into the switch sockets .
One at a time bypass all of the switches at their plugs.
Still no joy then make up some 2' to 3' long with a male at one end & a female at the other
Using the schmetic run these wires from one plug socket to the next in circuit.
A PIA job but if you had done this 4 pages ago you would be mowing by now .
If you can not be bothered to do this then let me know & I will ignore this thread while it grows to the size of War and Peace

 

[Rivets]

Aimme, you are overthinking everything, and assuming things about electrical troubleshooting on small tractors which is getting you deeper in trouble. I’ve been following this thread and agree with Bert’s last post. You need to go back to post #5 and start over. Don’t ASSUME anything and forget everything you’ve done so far. If you can’t do that then I too will be looking for others who need help. We are here to help you, but if you don’t want to follow the directions the experienced techs have to offer, then you’re on your own.

 

[BrianSki]

I also have a digital copy of the schematic. Not sure if I’m allowed to post it.

If it is on the device you are using to reply to the posts. Just above your where you are writing is a line with B I and some other things. If it is a picture, click on what looks like a picture, left of paper clip and it will let you post it. Or click on the paper clip and it will let you attach it

 

[slomo]

SO toss that multimeter back into the tool cupboard
Do as was suggested way way back in post # 5
Make up some shot jumpers ( patch cords actually ) with a male spade terminal ( Yanks seem to call the forks for some unknown reason ) so they plug into the switch sockets .
One at a time bypass all of the switches at their plugs.
Still no joy then make up some 2' to 3' long with a male at one end & a female at the other
Using the schmetic run these wires from one plug socket to the next in circuit.
A PIA job but if you had done this 4 pages ago you would be mowing by now .
If you can not be bothered to do this then let me know & I will ignore this thread while it grows to the size of War and Peace

War and Peace LOL.

slomo