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

[Telesis]

Correction: (I thought the D100 had the CVT auto trans but it doesn't! No drive pedal!) Your engine will die the moment you shift in reverse (with the blades engaged) unless you press the RIO button first!

 

[AimmeAshley]

If M and G are closed in the OFF position, then ign switch is working.
Bet the kill wire is grounded inappropiately (insulation worn off) between coil tab and ign switch.
I'd examine the length of the M wire on key switch to the coil tab.


If key OFF = yes grounded. If Key ON = no ground. If yes, bet the kill wire is grounded before key switch = bad.

Thanks for your response!

With the ignition switch ON (Run position) and with the kill wire disconnected from ignition coil, the ignition coil's ground tab measures continuity to ground, which I find bizarre. The ignition coil's ground tab is always ground regardless of the key position.

With the ignition switch OFF, the resistance of the kill wire to ground is less than 1 Ohm, which I think is correct.
With the ignition switch ON, the resistance of the kill wire to the ground chassis is roughly 9.89 KOhms, which I'm not sure is considered shorted to chassis.

I will look more into the kill wire and make sure it's not kinked somewhere. The kill wire is routed behind the starter motor, and I've have yet to take off, so I still have that section to check. I guess I'm afraid of removing the starter motor, but I'll have to do it to verify

 

[AimmeAshley]

Those two ”nubs” are the connection points for the transmission switch.

Is there any way to test this nub (or is this the switch)?

If I'm reading the schematic correctly, placing this in reverse should close this switch, right? So, in reverse, this should be shorted, and in any forward position, it's open?

 

[AimmeAshley]

On these engines, every time the flywheel turns, it produces a spark, the 12 volt system is out of the loop, and if 12 volts is introduced to this tab, it will destroy the coil. So if the engine runs fine without the coil hooked up, then your coil is fine, and your trouble is somewhere else.
When the coil is grounded by the switch/system, then the engine shuts off.

Thank you for your reply.

I've verified that there isn't any stray voltages on the kill wire. I tested it while switching between all the different combinations on the ignition switch.

 

[AimmeAshley]

Correction: (I thought the D100 had the CVT auto trans but it doesn't! No drive pedal!) Your engine will die the moment you shift in reverse (with the blades engaged) unless you press the RIO button first!

Thanks, I'm aware of that! In the John Deere D100 manual, it strangely calls this button, the "RIS" button.

 

[StarTech]

IF you are using the continuity tester buzzer on the meter then yes it will buzz as the primary side of the coil has a resistance of 1.5-1.7 ohms which is below the thresh hole for the buzzer to buzz.

As said you it runs with the kill detached which mean the coil is fine and that you have a short somewhere in the kill circuit. It was noted about the wires running behind the start and engine's crankcase getting pinched and causing a short circuit. I have seen this several times over the years where DIYers accidentally get the wires caught there.I even seen fuses to get blown this way too.

RIO is Reverse Inhibit Operation
RIS is Reverse Inhibit System

They are basically the same thing. Both prevent mowing in reverse unless activated.

 

[Fish]

. I tested it while switching between all the different combinations on the ignition switch.

Explain, I am not following.

 

[Telesis]

Your interpretation of the schematic w.r.t. the RIO switch(S6 on your schematic?) is correct! That switch is only closed when in reverse. The RIS switch(S4 on your schematic?) is the push button on the dash which activates the RIO latching relay(K1 on your schematic?). FWIW, I suspect JD calls S4 the RIS(Reverse Implement Switch) on the schematic because that's exactly how they refer to it in the text of the operating manual on p20 in the section "Using The Reverse Implement Option (RIO)" and because they already called S6 the RIO switch on the schematic!

 

[Ranamow]

Isn't there a one way diode that can go wrong on these systems?
One of the symptoms are, no spark with the kill wire attached.

 

[nobot]

Are you sitting on the seat when you're doing your testing? If not, did you bypass the seat's kill switch? If you answer both of these "No" then that's your problem.