TYM T353 HST electrical problem?

[Jon E]

Boy this one has me stumped. Started yesterday by getting on the tractor, started up immediately, ran it for close to 45 minutes, shut it down a couple of times while I was off the machine, but started right back up again within five minutes or so. I am not a big fan of letting the machine idle for more than a few minutes unless it's cold out. Anyway, I switched from bucket to pallet forks, put a pallet on the forks and drove it up to the house as I was going to load a bunch of totes on the pallet and bring them to my shed. Tractor was off for maybe 3-4 hours. When I went back out to start it again, I got on it, gear in neutral, held in the parking brake (just like EVERY other time I start the machine). The machine tried to turn over for about five seconds and then just stopped. Nothing. I turned the key again and nothing. Jiggled the pedals, moved the transmission lever (is a hydro model), turned everything off and back on again, nothing.

Opened the hood, checked the battery, 12.63 volts across terminals. When I turn the key, I can hear the fuel pump, the glow plugs "clicking", all the lights are working (4-ways, headlights, etc.) Electrical system appears to be getting full battery power.

Checked the starter, 12.39 volts at the starter, "jumped" the starter with a screwdriver (I know I shouldn't do that but HEY I gotta try everything), the starter spun & the machine tried to turn over again. Probably could have got it running if I wanted to weld a screwdriver to the starter terminals, but I'm not that stupid AND it wouldn't have solved my problem. Checked every fuse in the fuse box, all good. Checked every other fuse I could find, all good. Took the dash apart, checked the brake pedal safety switch, seemed to be working fine, not sure how to TEST it, but I can't imagine that's the problem.

So I have ruled out the following: battery, starter motor, fuses, brake safety switch, key switch, electrical wiring from battery to starter. The machine does not appear to HAVE a seat dead-man switch. I can't find any wires going to the seat and the machine does not shut off no matter when I leave the seat. So I don't think that's a problem either. The thing that struck me as odd is that it shut off in the middle of trying to start. Like the power to the starter was cut suddenly - or a fuse or relay blew.

So what do I try next? The dealer has been OK, not great but not particularly helpful. In this case, I called and was told that I should try to figure out the problem myself and if I was unsuccessful, call in the morning. Well, I'm unsuccessful but hoping someone here might be able to help...

 

[Ivan49]

Did you check our ground and clean the ground connections on the bat and where it hooks to the frame

 

[bigdeano]

Sounds like it could be the starter solenoid. I don't know which terminals you jumped with the screwdriver, so I may be wrong.

 

[myyaz33]

PTO button on?

 

[Jon E]

OK, spent some more time on this one today, still not solved. My brother is more of a mechanical type than I am so he helped out, but he doesn't have a lot of "tractor" experience. Everything I wrote above still holds true, we tested the battery and all fuses. We also checked the ground connections and the PTO was off. I also checked the switch that engages when the emergency brake is pushed.

He has a Snap-On remote starter switch which he brought over. When he connected it to the starter solenoid, he said that the solenoid "spun up" but did not engage the starter, whatever that means. All I know from a layman's perspective is that I heard a high speed electric motor whiz up, but no engine cranking. Same thing happened when I jumped the terminals with the screwdriver, but in that case, the tractor engine actually started cranking over.

Also - he checked the 70 amp relays mounted just above the battery, and was not convinced that they were in good operating condition. No real good way to test them, he said. Two of the three relays actually came apart (the plastic covers came off) while unplugging them from their sockets. I can't find relays until tomorrow. So the consensus among two relatively inexperienced guys is that either one or more relays are bad, or the starter itself is bad.

Anybody wanna chime in with hints or tips to figure this one out?

 

[Dave M7040]

I would like to understand what exactly you and your brother jumped at the starter.
I have provided an image of the Mitsubishi starter for your tractor with two red arrows on it.
If the jumping of the starter involves connecting the terminals with the two red arrows then you are not really jumping the starter in the way it is energized normally.
The starter solenoid needs to pull the starter gear into engagement with the flywheel and this is done by providing a 12 volt power source to a small terminal on the starter solenoid.
The connection can be from the battery cable terminal on the starter to a small terminal on the solenoid.

By jumping the two large terminals all you do is power up the starter motor without engaging the starter motor to the flywheel.
Get yourself a cheap test light like this one from Amazon and then we can start to tell you what and how to test your problem.
Amazon.com: INNOVA 3410 Test Light/Circuit Tester: Automotive
Dave M7040

 

[Jon E]

I would like to understand what exactly you and your brother jumped at the starter.
I have provided an image of the Mitsubishi starter for your tractor with two red arrows on it.
If the jumping of the starter involves connecting the terminals with the two red arrows then you are not really jumping the starter in the way it is energized normally.
The starter solenoid needs to pull the starter gear into engagement with the flywheel and this is done by providing a 12 volt power source to a small terminal on the starter solenoid.
The connection can be from the battery cable terminal on the starter to a small terminal on the solenoid.

By jumping the two large terminals all you do is power up the starter motor without engaging the starter motor to the flywheel.

Thank you for helping me understand this better. Yes, you are exactly correct, we jumped the two large terminals, which activated the starter motor but did not engage the flywheel. There is a small spade terminal on the solenoid (found reference to a "switch terminal"), on the engine side, which we did not see. There is 12+ volts across the large terminals on the solenoid but there is zero volts to the switch terminal. The connection to the switch terminal is through a separate wire from somewhere else - not the large positive terminal on the solenoid.

 

[Dave M7040]

Thank you for helping me understand this better. Yes, you are exactly correct, we jumped the two large terminals, which activated the starter motor but did not engage the flywheel. There is a small spade terminal on the solenoid (found reference to a "switch terminal"), on the engine side, which we did not see. There is 12+ volts across the large terminals on the solenoid but there is zero volts to the switch terminal. The connection to the switch terminal is through a separate wire from somewhere else - not the large positive terminal on the solenoid.

OK now the real test for the starter is to apply 12 volts to the "Switch" terminal. Remember you are bypassing all safety features on the tractor so be very careful. It could start and run away or run over you.
Best to have someone on the seat and the brake applied when doing this.
If the starter engages and turns the engine over then your problem lies in the circuit which supplies 12 volts to the "switch" terminal.
The 12 volt signal to this terminal will originate at the key switch but there may be a relay between the key switch and the terminal on the solenoid. There will be safety switches in this circuit as well such as one for the pto so you cannot start the engine with the pto engaged, The pto switches can fail.
Dave m7040

 

[Jon E]

A follow-up on this thread, as the problem is solved. Dave M7040 you were correct. Turns out that two of the three relays (70A, 12V) which are indicated as 'preheat relays' in the service manual, were bad. One or both is actually a starter relay. When I replaced it with a new relay, the machine fired right up. We were able to trace the small solenoid terminal back to one of them, although two of the three were in poor enough condition (corrosion and bad contacts) to be ineffective. These relays are mounted directly above the battery. The service manual is nearly worthless in identifying these parts or their correct location.

This is also one of those parts that you better hope your dealer has in stock. There ain't no substitute unless you are eager to do a fair amount of electrical work to rewire the system for a different type of relay. 70A 12V relays are commonly used in auxiliary lighting and cooling fan circuits in automotive applications, but none of what I was able to find was a close-enough match.

 

[Dave M7040]

Jon E
Thanks for providing an update. It is always helpful for those who provide advice to know when the advice turned out to provide some value.
Dave M7040