Snow L3400 HST starts but won't run in cold weather

[Chilly807]

I'm leaning more toward the safety switch, although why it would only do it when it's below freezing is a puzzle. Or, has the temperature not been above freezing since this first started happening and it's a coincidence?? Maybe there's ice in the seat switch?

Mine is a DT model (gear drive) so I'm not 100% familiar with the HST operation.. having said that, it seems to me that if you press the hydro pedal and the seat switch doesn't sense an operator present, it will shut the engine off. It sounds to me like that's what's happening.

If you want, I can check the service manual and see which pins have to be jumpered on the harness to bypass the safety switch, though I wouldn't recommend leaving it like that. Switches are relatively cheap, hospital stays or funerals are expensive as hel*!!

Keep us posted, this is an interesting one!

Sean

 

[TSO]

I'm leaning more toward the safety switch, although why it would only do it when it's below freezing is a puzzle.

It is a mystery. Possibly a loose connection to start with, and everything contracts a bit when it gets cold, so maybe the connection pulls apart?

Things get funny when they're cold ... my parking brake lever gets a bit sticky when it's very cold (single digits).

 

[Northeastern]

When you press the hst pedal and it stalls, does it stall like the key was shut off or does it labor and stall like someone pulling out and stalling a manual transmission? It sounds like a seat/safety switch to me also.

It does stall like the key is shut off. Will look at the seat/safety switch tomorrow- if I let up on the directional pedal fast enough, I can prevent it from stalling. Thanks.

 

[wmonroe]

It definitely sounds like the seat switch. Good luck.

 

[Northeastern]

I'm leaning more toward the safety switch, although why it would only do it when it's below freezing is a puzzle. Or, has the temperature not been above freezing since this first started happening and it's a coincidence?? Maybe there's ice in the seat switch?

Mine is a DT model (gear drive) so I'm not 100% familiar with the HST operation.. having said that, it seems to me that if you press the hydro pedal and the seat switch doesn't sense an operator present, it will shut the engine off. It sounds to me like that's what's happening.

If you want, I can check the service manual and see which pins have to be jumpered on the harness to bypass the safety switch, though I wouldn't recommend leaving it like that. Switches are relatively cheap, hospital stays or funerals are expensive as hel*!!

Keep us posted, this is an interesting one!

Sean

I would appreciate the info on how to bypass the switch. I have had to store the tractor outdoors and there has been snowy and icy weather. I sometimes have the seat pushed onto the steering wheel so icing on the switch is a possibility. I have owned the tractor for a little over a year. Thanks, this switch idea looks promising.

 

[Chilly807]

I'll try to look tomorrow, it may be as simple as the plate that presses on the switch needing a tweak away from the seat pan. There are three positions for the switch, one with the seat flipped forward to run the pto, one for "no operator present",, and one for "operator present" . It sounds like yours is either defective or not reaching that third position. I'm not sure if the hst range selector has a switch as well, it seems to me that there's only the seat switch and the pedal switch that control whether the engine runs or not when the pedal is depressed and theres someone in the seat, or not.

Sean

 

[Coyote machine]

I would appreciate the info on how to bypass the switch. I have had to store the tractor outdoors and there has been snowy and icy weather. I sometimes have the seat pushed onto the steering wheel so icing on the switch is a possibility. I have owned the tractor for a little over a year. Thanks, this switch idea looks promising.

Your objective is to bypass the seat switch to fool it into completing the circuit and allowing the tractor to move. To do this locate the seat switch on the bottom of the seat. Disconnect the wiring connector so the seat section stays on the seat bottom and jumper a piece of wire/paper clip across the contacts of the wires NOT attached to the seat. Start tractor and drive it forward/reverse. If you can now drive it the seat switch is an open circuit at the seat which needs to be fixed. If no forward/reverse the switch is not the problem.

 

[Northeastern]

Your objective is to bypass the seat switch to fool it into completing the circuit and allowing the tractor to move. To do this locate the seat switch on the bottom of the seat. Disconnect the wiring connector so the seat section stays on the seat bottom and jumper a piece of wire/paper clip across the contacts of the wires NOT attached to the seat. Start tractor and drive it forward/reverse. If you can now drive it the seat switch is an open circuit at the seat which needs to be fixed. If no forward/reverse the switch is not the problem.

Thanks, will try and report back tomorrow.

 

[Chilly807]

Ahh, but you've not taken into account the devious cunning of the Kubota designers.. Our Japanese amigos have no less than 4 wires (iirc) going to that switch, it might even be 6, I'll have to look at mine and the service manual to see which wires do what. As I recall, the wiring diagrams are pretty good, the three functions of the switch are separated and easier to see.
It may even be as easy as adjusting the tab that actuates the switch, mine needed a small tweak one time.

Sean

 

[Coyote machine]

Ahh, but you've not taken into account the devious cunning of the Kubota designers.. Our Japanese amigos have no less than 4 wires (iirc) going to that switch, it might even be 6, I'll have to look at mine and the service manual to see which wires do what. As I recall, the wiring diagrams are pretty good, the three functions of the switch are separated and easier to see.
It may even be as easy as adjusting the tab that actuates the switch, mine needed a small tweak one time.

Sean

So now I know why you guys pay all the extra $$$ to buy your brand?! For switches that keep the tractor from running...:laughing:
Yes, OP, follow what the guys who have Kubotas tell you when it comes to which two wires to jumper, OR first see if the seat switch connector has come loose, or a loose wire, or spring tab, BEFORE you disconnect it.