KIOTI HST locking up in reverse

[krmoto]

Hi Guys, just wondering if anyone can shed some light on this problem, l just purchased a 2014 NX4510 hst, when traveling in reverse and take foot off pedal it tries to slow for a second or so then locks up sharply, forward is fine although it will creep forward at idle a little and bit more with more rpm, does this sound like it needs a hst reset?

 

[justman777]

Think it needs one of two things...possibly three.

1. Pedals re-calibrated. I posted the instructions on this forum somewhere...

2. New potentiometer for the reverse pedal.

3. New program for the TCM (must have dealer do this).

Recommend you try recalibrating the pedals first before trying something else.

 

[krmoto]

Think it needs one of two things...possibly three.

1. Pedals re-calibrated. I posted the instructions on this forum somewhere...

2. New potentiometer for the reverse pedal.

3. New program for the TCM (must have dealer do this).

Recommend you try recalibrating the pedals first before trying something else.

Many thanks, found your HST recal post on the calibration light thread posted few months ago, will try that and see how we get on.

 

[justman777]

Cool. If the calibration doesn't work, you may ask a local dealer about a TCM software update. Mine was doing something similar, and I had a tech come out and drive it. He wondered how the previous owner even drove the thing. It was pretty bad. After the update, everything's been okay, except for a bit of a stutter when trying to go very slow in reverse.

Best wishes!

 

[krmoto]

Cool. If the calibration doesn't work, you may ask a local dealer about a TCM software update. Mine was doing something similar, and I had a tech come out and drive it. He wondered how the previous owner even drove the thing. It was pretty bad. After the update, everything's been okay, except for a bit of a stutter when trying to go very slow in reverse.

Best wishes!

Thanks for the tips, been a bit hectic here but now had time to have a play with it, by driving forward up a steep hill and stopping l found that it won't run backwards which is kind of a handy thing, because the tractor is new to me i'm not sure if this HST system should be able to free wheel or should lock eventually after comes to standstill like a auto trans brake, l found the both modules either side of the seat were unbolted so something has been played with so l'm a bit scarred of trying a calibration at the moment just incase make things worse so l tried a washer under the reverse pedal stop to try trick the TCM but then it would not start because it made the CAL light come on, will post any progress.

Cheers

 

[RickB]

Cool. If the calibration doesn't work, you may ask a local dealer about a TCM software update. Mine was doing something similar, and I had a tech come out and drive it. He wondered how the previous owner even drove the thing. It was pretty bad. After the update, everything's been okay, except for a bit of a stutter when trying to go very slow in reverse.

Best wishes!

That probably had something to do with the previous owner NOT driving it any more. Part of the beauty of computer controlled hydros and power shifts is many symptoms can be cured by a recalibration, reflash or new potentiometer.

 

[krmoto]

Thanks for the tips, been a bit hectic here but now had time to have a play with it, by driving forward up a steep hill and stopping l found that it won't run backwards which is kind of a handy thing, because the tractor is new to me i'm not sure if this HST system should be able to free wheel or should lock eventually after comes to standstill like a auto trans brake, l found the both modules either side of the seat were unbolted so something has been played with so l'm a bit scarred of trying a calibration at the moment just incase make things worse so l tried a washer under the reverse pedal stop to try trick the TCM but then it would not start because it made the CAL light come on, will post any progress.

Cheers

Have now discovered that after using this tractor for 15-20 mins it appears to pull up to a stop in reverse in a controlled manner as it should, oil warm or possibly other cause? Also had a play with the knob that adjusts the distance of pulling up and there is no noticeable change forwards or reverse, but would say it's pulling up quite fast.

 

[justman777]

Still say you need to run a re-calibration. The procedure can be a bit daunting, but it's another step in the troubleshooting process and doesn't cost anything.

FYI, I tried to re-calibrate my pedals a few times before I gave up and called the dealer. He sent out a technician to update the TCM / ECM. Afterwards, the tractor stopped throwing me around by stopping in a controlled manner, both forward and reverse.

Also, I don't know the viability of putting anything on the tractor that affects pedal travel. The pedals are attached to potentiometers that vary the amount of current going to the TCM and ECM based on how much you push the pedal down. The only thing you're doing by putting something (a washer) in the travel path is limiting the amount of voltage supplied by the potentiometer, and thus limiting your travel speed. It shouldn't do a thing for slowing you down.

 

[krmoto]

Thanks justman do appreciate your input, sounds like yours was doing the same thing in both directions, yes cal seems a bit daunting, just to fully explain what l did, l wanted to try and lesson the braking (locking) affect in reverse only, it was impossible to control with my foot, had a look underneath at pedal box and each pedal has a rubber stop in rest position, so l put a 1.5mm washer in place which is a small amount in reverse rest pedal position, so in theory the pedal position/potentiometer should now tell the controller/actuator slightly less braking force, anyway the washer was enough to throw the cal light on so not able start the tractor to see if it made a difference, so this made me think the cal cant be too far out if the washer made the cal light come on, l could of started the tractor first then put the washer in but there was no point if it cant be fooled and won't start, anyway nothing ventured nothing gained, so its back to try calibrate, just don't want to make anything worse if that's at all possible. will post outcome, Cheers.

 

[justman777]

Look forward to hearing what you find out!

Just FYI, the potentiometer doesn't necessarily "brake" when you lift up on the pedal. It just tells the TCM to slow down or stop when you lift off. In this case, what I think is happening (potentially) is the voltage from the pedal potentiometer is dropping erratically or the value is set incorrectly, so the TCM detects no voltage at some point and it just stops the transmission in response. That's the "braking" effect you're getting.

 

[krmoto]

Yes do understand what you are saying, l have 7 hst machines in total, the kioti is the only machine with potentiometer/actuator HST control, all the rest are good old plain and simple linkage, even my Bobcat T200 (fully hand control) which is loaded with POT/ACT control has linkage HST, all these other machines just slow up nicely with a kind of braking resistance, thats why l like HST its so easy to use and in my experience seems a tuff and trouble free transmission but l have not got a clue how it works because never had any probs (yet) touch wood.

The thing that baffles me is the fact that the problem goes away when the tractor warms up, so think this is a clue to the problem and would suggest voltage control is ok, up until this l didn't think HST systems could actually lock up completely, but you learn something every day, but if you still think its elec? l need get multimeter on potentiometer and see if voltage is rising smoothly.
Also if the stopping distance gadget was working l might be able to dial the problem out?
Cheers

 

[justman777]

I really loved the simplicity of my first tractor--JD2305. You push on the pedal it goes. You let off the pedal it stops. But, it didn't have cruise control, no stall, etc. I guess every "feature" comes with a price, and in this case, the "price" is simplicity. I bought this tractor for the features and larger frame size, but I think if I had to do it all over again, I'd go with something a little simpler, like the DK series.

BTW, I've never noticed a difference in stopping distance using the dial thing. All seems like the same to me. The auto-throttle is handy, as is the cruise control. Never use the no-stall, which probably means I haven't really pushed it hard enough.

It's a good idea to probe for voltages. If it goes away when it's warm, may have something to do with metal expansion or grounds. You could try cleaning your grounds and see what happens. Several members on here have said there grounds are painted over and didn't really have good contact.

 

[krmoto]

Update, have now tested the 2 wires (forward and reverse) for voltages that feed the actuators which go through a hole into the transmission casing, the actuators are buried in the transmission so would need to split tractor to get at them, the voltage is 10.31v with pedals in rest position and 10.71v fully depressed, both forward and reverse read much the same only 0.1 difference so l would say cal is ok, the only thing l found a bit strange when pressing the pedals gradually is the voltage stays at 10.31v until the pedal reaches a point then the voltage jumps from 10.31v to 10.51v ish then rises gradually through to 10.71v fully depressed, both pedals do the same thing, whilst underneath l noticed that paint was off the eng/transmission nuts so think someone has been in there at some point.

Also checked the HST response dial, this has 5v feed and the output varies from 0.2v to 4.75v when fully turned, did a drive test with a marker and it does make a difference on how far it travels before stops, so it does work but you wouldn't really notice otherwise, when the dial is turned fully to the left the it takes longer for the tractor to stop.

 

[cutthroat]

Just wanted to add my two cents on this thread. I have a NX6010 HST. I was having this same problem, it was acting up in both directions. For me this issue happened after being loaded on a trailer and transported about 80 miles. I would push on the pedal, it would be slow to respond, then respond, when I would let my foot off, it would keep going and then suddenly brake. I called my dealer, he replaced the potentiometer. This made no difference. We then decided to take it back to his shop to look at. Loaded it up on my trailer, transported about 100 miles. Got to dealer and problem was gone. Problem hasn't came back since. We chalked it up to some sort of loose connection somewhere. We did do some extensive checking of all connections but couldn't find anything loose. I will reach out to him and look into the computer update.

-Craig

 

[krmoto]

Well Craig ive heard of some strange things ever but that takes some beating, the general life of a tractor is bumping/shaking around so l would be surprised if connection fault, but can't think of any logical reason it would right itself by going for a trailer ride, magic comes to mind

Just wanted to add my two cents on this thread. I have a NX6010 HST. I was having this same problem, it was acting up in both directions. For me this issue happened after being loaded on a trailer and transported about 80 miles. I would push on the pedal, it would be slow to respond, then respond, when I would let my foot off, it would keep going and then suddenly brake. I called my dealer, he replaced the potentiometer. This made no difference. We then decided to take it back to his shop to look at. Loaded it up on my trailer, transported about 100 miles. Got to dealer and problem was gone. Problem hasn't came back since. We chalked it up to some sort of loose connection somewhere. We did do some extensive checking of all connections but couldn't find anything loose. I will reach out to him and look into the computer update.

-Craig