GR2120 wiring of timer relay and no shut-off condition

[Maso]

Hello,
The first symptoms were a rapid clicking of the stop solenoid and then the machine would not shut off.
What I did so far: replaced the timer relay. Put 12v directly to the stop solenoid and observed it move the rod and hold. Replaced the PTO switch and confirmed function of the seat switch and brake switch. Measured 12.7 volts on the timer terminal Red wire; read negligable voltage on the Black White terminal Wire. Could not measure continuity between the Yellow Black terminal wire and the YB at the solenoid.
Here is a picture of the terminal connections:


View attachment 113348

And here is the diagnostic from the Work Shop manual.

Here is what I think is the wiring diagram from the WSM.

What I don’t know: 1. Whether the Yellow black wire from the timer connector goes directly to the YB that emerges from the loom next to the 40 A fuse in the engine compartment 2. Why the colors of the wiring diagram differ from mine at the timer connector 3. Why I read no battery voltage on the Black White wire.
Further evidence: the 15 A fuse under the cowel is good. I read 12 v on the red fuse wire and zero on the gray wire. I read 12 volts across the seat switch (Yellow White)
I posed enough puzzles for now and would appreciate any insights and advice.

 

[Maso]

Does anyone else have a 14 gauge BlackWhite wire at the terminal of the timer relay? If so, would you check to see if it gets 12v with the key in first position?

 

[jaxs]

Hopefully someone sheds light on wire colors for you but if not, here's something to think about. I can see by what you've said that you are comfortable with electrical systems. Kubota's wiring harnesses are impractical and overly complicated, commonly called Rube Goldberg. When me and those sharing my shade tree find it necessary to troubleshoot electrical on these tractor (easily 50% of total problems) we eliminate unnecessary wiring and devices while in there. If I understand correctly widgets that are supposed to operate the fuel shut off are malfunctioning. As far as I can determine the ONLY reason for widgets is making it unnecessary to push and pull a knob like we did for decades. Can you install a cable similar to old school manual chokes and widely used for various functions on lawn mowers? If relay is involved with safety switches you sound like it wouldn't be hard to rewire them in the process. Some of us that live on the edge do away with safety switches but that isn't what I'm recommending to you.

 

[Maso]

Hopefully someone sheds light on wire colors for you but if not, here's something to think about. I can see by what you've said that you are comfortable with electrical systems. Kubota's wiring harnesses are impractical and overly complicated, commonly called Rube Goldberg. When me and those sharing my shade tree find it necessary to troubleshoot electrical on these tractor (easily 50% of total problems) we eliminate unnecessary wiring and devices while in there. If I understand correctly widgets that are supposed to operate the fuel shut off are malfunctioning. As far as I can determine the ONLY reason for widgets is making it unnecessary to push and pull a knob like we did for decades. Can you install a cable similar to old school manual chokes and widely used for various functions on lawn mowers? If relay is involved with safety switches you sound like it wouldn't be hard to rewire them in the process. Some of us that live on the edge do away with safety switches but that isn't what I'm recommending to you.

I appreciate your vintage preferences, which I share and use on my 1946 Ford flathead truck. Kubota‘s engineers certainly devised a complex system to shut off the damn engine. I have a lawn mower choke cable at hand if my last ditch intuition does not work.
I noticed that the Yellow Black wire to the relay matches the colors of one wire going to the “Acc” terminal on the ignition switch. Were they were thinking the shut off solenoid is an “accessory”? OK. The Acc terminal is supposed to be turned on at the first click. There is no continuity on mine, however. A ha! When the Kubota dealer opens Tuesday, I can probably buy a new switch and check the continuity. Presumably the Acc sends 12v to the YB wire on the relay terminal; when the switch is turned off, maybe the relay sends a signal to the stop solenoid and the rod pulls the fuel valve shut. If none of that happens, I’ll just rig the choke cable to pull the lever when I want to stop.