2006 NH TC55DA clutch disengages randomly

[FarmaBro]

Today I removed the ehss module and potentiometer so I could bring them inside where it's warm and dry. The repair manual says the pot output should be 3.2V when the pedal is depressed so I was surprised when I connected my 12V supply and found that output voltage increases when the pedal is pressed. Could the manual be incorrect? No. It's the input voltage that wrong. With a 5V supply, I saw close to 3.2V near the end of the pot lever travel. Pot is fine, I'm sure.

Now all three wires from the pot connect directly to the EHSS module which means one pin (#6) is supplying 5V to the pot. I powered the EHSS module from my bench supply and found that sometimes I could get a 5V reading out of pin 6 but most of the time, it read 0.3V. That's no good. I have a strong suspicion that the 5V regulator in the EHSS module is no good. Of course the thing is potted in resin so I won't be getting it apart without breaking it irreparably. Why is it always the most expensive parts that break?!?!?!?!?!

Here's a picture of my setup for those who care to see it.

 

[LouNY]

Good work, it would be nice if the manufactures would make test points in their products,
but that's not going to happen.
I think of the service/ repair manuals that the military has or at least for for there electronics,
pull the cover of a radio and every circuit board had several labeled test points and the manual
had the expected voltage and waveform and what to lock at if it was wrong. Of course this was back in the early 70's.

 

[MBeam]

Today I removed the ehss module and potentiometer so I could bring them inside where it's warm and dry. The repair manual says the pot output should be 3.2V when the pedal is depressed so I was surprised when I connected my 12V supply and found that output voltage increases when the pedal is pressed. Could the manual be incorrect? No. It's the input voltage that wrong. With a 5V supply, I saw close to 3.2V near the end of the pot lever travel. Pot is fine, I'm sure.

Now all three wires from the pot connect directly to the EHSS module which means one pin (#6) is supplying 5V to the pot. I powered the EHSS module from my bench supply and found that sometimes I could get a 5V reading out of pin 6 but most of the time, it read 0.3V. That's no good. I have a strong suspicion that the 5V regulator in the EHSS module is no good. Of course the thing is potted in resin so I won't be getting it apart without breaking it irreparably. Why is it always the most expensive parts that break?!?!?!?!?!

Here's a picture of my setup for those who care to see it.
View attachment 676731

Hey, I’m having the same problem with my tc55da except it still disengages in all the gears and requires me to shut the engine off and back on for it to temporarily work. What did you find was the problem?

 

[jonathentyquan]

2006 TC55DA w EHSS

Ladies and Gentlemen,

After spending too much time troubleshooting everyone's favorite type of problem (intermittent), I am out of ideas and so I come seeking the collective knowledge of this community. Please bare with me while I try to explain.

While travelling, the clutch randomly disengages and in order to resume motion, I must depress the inching pedal. I know that this pedal operates both a potentiometer and a dump valve so I manually actuated each and found that it is pushing the pot through it's full range of motion (or most of it) that permits driving again. This leads me to believe the EHSS controller may be getting a bum signal from something. It may think the tractor has just been started or the operator has left the seat.

I don't believe the problem is the seat switch because I first noticed this when hogging my field and the engine should turn off when the pto is running and the operator leaves the seat. Also, my seat switch is broken and bypassed.
Nox Vidmate VLC
I believe the clutch is physically fine because it feels very grabby when I engage it hard via the pedal but also, I can stall the engine by pressing the breaks.

I don't believe the problem is hydraulic pressure because I don't find the problem is exacerbated by operating the pto and loader while travelling.

I checked the potentiometer and found the resistance changes relatively smoothly throughout it's range of motion from ~200ohm to 1.4kohm. It's times like this when I wish I had an old style multimeter with a needle. I don't know what these values should be but my measurements were repeatable.

System voltage is >13V while running. I expect the electronics should operate just fine between 10V - 14V

Oil is clean and full with a brand new filter.

My inspection revealed no damage to any wires. Ground lug is in good condition and when I pulled on the wiring harness while driving, I could not cause the problem to manifest in a repeatable way.

I have a service manual on order but it won't arrive until next week. Hopefully it can give me more insight into how the various systems operate. A more reasonable person would wait but I can't let it go. I'm not satisfied without understanding.

If I have made any incorrect assumptions, please correct me. If anyone has insight to share, I sure would appreciate it.

This sounds like a good challenge and I’m looking forward to following along.

 

[Dave3000]

FarmaBro, did you ever figure out the issue? My TC55DA has the same exact problem. I topped off the transmission fluid, changed the fuel filter, and replaced the EHSS module, but the problem persists. I'm really hoping you let us know what you figured out.

 

[Mike1955]

2006 TC55DA w EHSS

Ladies and Gentlemen,

After spending too much time troubleshooting everyone's favorite type of problem (intermittent), I am out of ideas and so I come seeking the collective knowledge of this community. Please bare with me while I try to explain.

While travelling, the clutch randomly disengages and in order to resume motion, I must depress the inching pedal. I know that this pedal operates both a potentiometer and a dump valve so I manually actuated each and found that it is pushing the pot through it's full range of motion (or most of it) that permits driving again. This leads me to believe the EHSS controller may be getting a bum signal from something. It may think the tractor has just been started or the operator has left the seat.

I don't believe the problem is the seat switch because I first noticed this when hogging my field and the engine should turn off when the pto is running and the operator leaves the seat. Also, my seat switch is broken and bypassed.

I believe the clutch is physically fine because it feels very grabby when I engage it hard via the pedal but also, I can stall the engine by pressing the breaks.

I don't believe the problem is hydraulic pressure because I don't find the problem is exacerbated by operating the pto and loader while travelling.

I checked the potentiometer and found the resistance changes relatively smoothly throughout it's range of motion from ~200ohm to 1.4kohm. It's times like this when I wish I had an old style multimeter with a needle. I don't know what these values should be but my measurements were repeatable.

System voltage is >13V while running. I expect the electronics should operate just fine between 10V - 14V

Oil is clean and full with a brand new filter.

My inspection revealed no damage to any wires. Ground lug is in good condition and when I pulled on the wiring harness while driving, I could not cause the problem to manifest in a repeatable way.

I have a service manual on order but it won't arrive until next week. Hopefully it can give me more insight into how the various systems operate. A more reasonable person would wait but I can't let it go. I'm not satisfied without understanding.

If I have made any incorrect assumptions, please correct me. If anyone has insight to share, I sure would appreciate it.

Farm bro I commend you on a complete analysis of your machine. You have covered your bases. And I seriously doubt the manual is going to be any help. Let us know because when you find the problem I’ll bet it’s going to be so simple and obvious. Have fun these don’t come along often!