L39 GST dies when it begins to move

dkyle · Mar 19, 2019

I just bought a 2008 L39 GST. Ran fine the day I bought it; but now that I am using it I notice it will intermittently die as I let out the clutch. Sometimes it will die while driving it. I sense when it wants to die, I immediately push in the clutch & rev it back up to prevent it from stalling. I can go 1/2 hour without a problem, then it may stall once, or a few times in a short period.
I have never had it stall while operating the backhoe, only when engaging the clutch, & a few times while driving it.
Once I couldn't move, it would constantly try & stall as I let out the clutch. It finally was able to go after the 5th attempt.
I bypassed the seat kill switch.
Any ideas what could be wrong?

North Idaho Wolfman · Mar 20, 2019

First and foremost, get out of the habit of using the mechanical clutch.
You don't use the mechanical clutch for movements operations on a GST, it's main purpose is for PTO operations.
It wears at a 1000 times the rate of the hydraulic clutch.

You use the shuttle lever for all forward and reverse operations, Yes you can use the mechanical clutch for operations when small precise movements are needed like hooking up to an implement or maneuvering in tight places.

Now for your issue of it shutting off, The seat switch (there could be two) is the most likely candidate for the issue, it's probably maladjusted.
Check that and report back.

dkyle · Mar 20, 2019

I bypassed the seat switch the first day I got it.

Since my initial post, the problem is now worse. I can't seem to move it at all.
Not using the clutch now; when I shuttle forward, it clicks & starts to stall. I shuttle in N to keep the engine running. I shuttle forward or reverse & it "clicks" & starts to stall. I can keep the engine running only when I shuttle back in N.

I hear a click and it stalls. Something is acting like a kill switch. What can it be sensing, & what is it switching?

North Idaho Wolfman · Mar 21, 2019

That model has an ECM (electric control module) and a OPC (occupancy control computer) both of which could be the source of your issue along with other sensors, inputs and outputs.
Randomly shorting wires or probing could get you in a lot of trouble.

I personally suggest you get the WSM and it will have a step by step troubleshooting procedure in it.
P/N 9Y011-13252

In the meantime check all fuses and electrical connections on the tractor.

dkyle · Mar 25, 2019

while I wait for the WSM to arrive I would like to ask what the ECM is looking at (besides the OPC) when the shuttle is engaged & it decides whether or not to kill the engine.

North Idaho Wolfman · Mar 25, 2019

dkyle said:
while I wait for the WSM to arrive I would like to ask what the ECM is looking at (besides the OPC) when the shuttle is engaged & it decides whether or not to kill the engine.

PTO switch, seat switch or switches, position of shuttle lever, just off the top of my head.

dggott · Mar 25, 2019

Here's the link to the WSM I use on my BX2200. Might check and see if the same site has one for your model and end your wait. Unless your internet is as slow as ours, in which case, the physical one may get to you before it finishes downloading.

https://www.kubota.cz/data/soubor/WSM_BX1800_2200_EN.pdf

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L39 GST dies when it begins to move

dkyle

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North Idaho Wolfman

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dkyle

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North Idaho Wolfman

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dkyle

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dggott

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