G'day Skramer

Before I answer your question I will have to save the diagram to desktop and enlarge to track the circuits, in the meantime, get your self a length of insulated wire and connect one end to the positive pole on the battery or the hot connection on the starter solenoid and disconnect the connector at the stop solenoid, place the hot wire to the stop solenoid connection and listen for the click, if there is a click, then the tractor should start, make sure it is neutral beforehand, you can operate the tractor in this mode if you need the use of it, just have to remove the hot wire to stop the engine.

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After re-reading your post, it seems like your start system has failed (starter), I would suggest you check from #29 through to #33, these being seat (bypassed), mid PTO, transmission shift lever, rear PTO and the park brake, these are all sensors in the start circuit and if any are not in the neutral or applied position (park brake), the engine wont start, at best, the relays #19 and #23 have their groundings through the sensors quoted, #10 the fuel cut solenoid has its own grounding point through the body, #13 is the main circuit ground and there are a number of items that have their own grounding, I could spend hours trying to trace the circuits and even with the diagram enlarged doesn't help much because of distortion of the important areas.

If you want to try to start the tractor, make sure the tractor is in neutral and using a remote start switch connected to the battery supply terminal on the solenoid and the other end to the small starter spade on the solenoid, ignition on and press remote starter button and see what you get, if the engine doesn't start but cranks over, then hook up the bypass for the kill solenoid and retry, if still no start or no click at the fuel solenoid, you will have to check for continuity of the windings of the fuel kill solenoid before replacing, you may have some testing with a multimeter to do of the start circuit, I would be checking for starters the start relay #16 and the kill solenoid relay #23, both relays have a power through circuit and a pull in circuit, in most cases the pull in windings fail or the power through contacts inside the relay get burnt, you could also remove the connectors from each relay and push on and off a few times, the relay spades get dirty and wont make circuits, and this will give you a no-start too.

 

So, the problem with an intermittent issue is that it can start working again before you find the trouble. I went up to the pole barn where the tractor is parked and started doing some wire tracing and testing with my meter. I didn't know where the different components were or what they looked like specifically. I knew there were three easily accessible under the hood, so I started there. The three under the hood are the flasher relay, the glow plug timer and the safety start relay. I start unplugging them and plugging back in and the thing started, of course. I was pretty sure I hadn't fixed it, so I figured I would at least try to find all the other relays etc. The seat safety switch timer, diode, and kill relay are all under the seat.
For some reason, I had the notion in my mind that the seat safety switch timer might be the issue. So I figured I would unplug it and see what happened. With that seat safety switch timer unplugged, the tractor behaved the same as when it wouldn't start, all the dash lights behave properly but nothing else. Since the seat switch is already bypassed, I decided that the timer for it wasn't doing anything, safety wise anyway, so I bypassed it. I guess I'll see if that was the issue as time goes on. If it isn't the issue, it's one less thing to test next time. Anyway, long post to say for now it's fixed.
And thanks Fred for taking the time to try and help.

 

Lets hope you found the problem.

 

My TC30 had the same problem. I isolated the problem to the safety controller on the firewall on the right side of the engine bay. That part is available from the dealer for $700. I said no way! So, see my post on how to bypass the safety controller. Tractor will NEVER have that problem again but you need to be careful when starting the machine. DON'T be standing in front of the rear wheels and try to start it in gear. It could run over you!

 

Where is your post for TC30 problem?