NX 5010HST Cab reverse intermittent and jerky

[TN8Man]

I had my reverse get squirrely (intermittent jerking) after a long day of bush hogging last year and eventually it stopped working all together. The dealer (not where I bought it) picked it up and returned it saying it's fixed. Then a few weeks ago it started all over again, another long day using the PTO, reverse started getting squirrely and then it gave out again. This time I get it back into the barn and the next day it started up and the reverse worked fine.

I brought it to the dealer and they claim they can't get it to fail so they don't know what went wrong on me. I explained the long day of use before it went out so they are thinking either a intermittent electrical connection or a coil that controls a valve that makes it go in reverse might be acting up when it gets hot.

Has anyone heard of this failure mode before and might have an idea what it could be?

The dealer is going to keep trying to get it to fail but says he can't replace a part that isn't failing.

thanks

 

[justman777]

Sounds like a calibration issue or air intrusion issue. Mine is doing the same thing, but only does it after it gets nice and warm and the hydro fluid has a chance to get nice and aerated. Notice any odd sounds in your unit when sitting still, like the one in this video? YouTube

Sounds like an intermittent chugging sound, like a pump hitting an air pocket. The sound is slight, but you can still hear it if you turn up the volume. This is my tractor, and it only does it after the fluid is good and warm and has an opportunity to get air into it via a suction side air leak. Have your dealer replace the hose in the suction side with a piece of clear tubing and see if air bubbles are going through it. If it does, you have a suction side air leak.

The alternative is the reverse potentiometer is going out and either needs to be calibrated or replaced.

 

[TN8Man]

That's good info Thanks!

My tractor is still in the shop but I will ask about this. My thinking was it could be related to heat since the problem only surfaces after hours of operation.

 

[justman777]

That's good info Thanks!

My tractor is still in the shop but I will ask about this. My thinking was it could be related to heat since the problem only surfaces after hours of operation.

The challenge with getting a dealer to replicate the issue is that they have to create the same conditions that existed when the issue surfaced for you. That means getting everything hot, and that usually takes some time. They won't be able to get replicate the issue if they just hop in, crank it up, and hit the reverse pedal. It takes time.

They should be able to test the potentiometer to rule that out easily enough. The potentiometer is just like the gas pedal in most modern cars in that in should have a voltage output that either increases or decreases gradually from a set voltage as the pedal is actuated with no abrupt spikes or dips. The voltage is used by the Transmission Control Module to control the HST, telling it how fast or slow to go. Any sudden spikes or dips in voltage indicates the potentiometer is acting up and should be replaced.

 

[TN8Man]

The challenge with getting a dealer to replicate the issue is that they have to create the same conditions that existed when the issue surfaced for you. That means getting everything hot, and that usually takes some time. They won't be able to get replicate the issue if they just hop in, crank it up, and hit the reverse pedal. It takes time.

They should be able to test the potentiometer to rule that out easily enough. The potentiometer is just like the gas pedal in most modern cars in that in should have a voltage output that either increases or decreases gradually from a set voltage as the pedal is actuated with no abrupt spikes or dips. The voltage is used by the Transmission Control Module to control the HST, telling it how fast or slow to go. Any sudden spikes or dips in voltage indicates the potentiometer is acting up and should be replaced.

That's interesting info. A potentiometer is a variable resistor. A bad pot is when the resistance value change is erratic and/or resistance increase/decrease change is not linear. It would make sense that if the voltage derived from the pot controlling the transmission is erratic then this could explain what I'm experiencing. Not sure how heat would factor in though but it probably could.

I would like to find a source for information on how the systems work on a modern day tractor and specifically my tractor. That would help me tremendously. Do you have a link to such information?

Thanks

 

[justman777]

That's interesting info. A potentiometer is a variable resistor. A bad pot is when the resistance value change is erratic and/or resistance increase/decrease change is not linear. It would make sense that if the voltage derived from the pot controlling the transmission is erratic then this could explain what I'm experiencing. Not sure how heat would factor in though but it probably could.

I would like to find a source for information on how the systems work on a modern day tractor and specifically my tractor. That would help me tremendously. Do you have a link to such information?

Thanks

Unfortunately, I don't. What I listed above is based on my analysis of the HST components, deductive reasoning, and experience dealing with modern vehicles....but mostly deductive reasoning. The way I figure, the forward/reverse pedals actuate their respective potentiometers which send voltage signals to the TCM. Deviations from the reference voltage are interpreted by the TCM as forward/reverse signaling, and the TCM adjusts the HST appropriately. At the same time and when "linked pedal" is engaged, the TCM signals the ECM to adjust engine speed based on deviations from the reference voltage to control/adjust engine RPM. Someone with a workshop manual should be able to supply the potentiometer reference voltage.

 

[TN8Man]

That's okay, the information you provided is helpful and motivates me to learn more. I needed to buy an online service manual anyway so I'll start with that.

Anyone know the best site to purchase a pdf copy of the Kioti service manuals?

 

[justman777]

That's okay, the information you provided is helpful and motivates me to learn more. I needed to buy an online service manual anyway so I'll start with that.

Anyone know the best site to purchase a pdf copy of the Kioti service manuals?

Unless something has changed VERY recently, you won't find an online manual. I've searched high and low and chased thread after thread trying to find one. I even aske Kioti corporate if they have a PDF version for sale, and they said "No". I then asked why not, and they said "Because South Korea wanted it that way". That's verbatim what I got from Kioti "customer service". What a joke.... Kioti does sell a hard copy service manual for a bit over $200 I think.

 

[cjoffutt]

Unless something has changed VERY recently, you won't find an online manual. I've searched high and low and chased thread after thread trying to find one. I even aske Kioti corporate if they have a PDF version for sale, and they said "No". I then asked why not, and they said "Because South Korea wanted it that way". That's verbatim what I got from Kioti "customer service". What a joke.... Kioti does sell a hard copy service manual for a bit over $200 I think.

Someone needs to scan and upload it....I'd take one for my NX5010 HST.

 

[TN8Man]

In my research I stumbled across this thread on Tractorbynet where it appears a pdf version might exist.

I have also seen a few online sellers that claim you can buy and download the manual (like this one) but it could be a scam so I have not pulled the trigger yet and the reason why I asked the question here.