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?
KIOTI HST locking up in reverse
- Thread starter krmoto
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justman777
Platinum Member
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.
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
Platinum Member
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!
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
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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.
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
Platinum Member
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.
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.
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
Platinum Member
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.
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.
