Cat 140H Forward and Reverse Clutch won't engage

[Sepult]

Hi,
I've got a 140H S/N APM00296 that's got an intermittent, but almost constant now, issue with travel. We've lost all forward and reverse gears.

It was working when parked over winter. This summer when we started it we had no travel. We had active codes for intermittent/erratic signal from the transmission control/shift lever, as well as output speed sensor #1 erratic signal. We replaced the speed sensor, and the repaired the F/R switch in the shift lever. The speed sensor code still appears, although the wiring is OK from the ECU to the sensor. I'm assuming that this code is being caused by the ECU expecting there to be motion on the output shaft but there isn't, so it's throwing the code.

We're getting the correct pressure in every gear forward and reverse except for station A and B. They're 0 PSI. Except occasionally, we've gotten it to kick in and work perfectly and the pressure is normal and operation is normal, including shifting gears. Once it does it works until we shut down and allow it to sit. Then, same problem again.

I'm thinking a stuck modulation spool because it's also very harsh shifting when it does work, and the inching pedal doesn't have much response. So I was thinking of pulling the valve bank and inspecting. But an older, more experienced tech I know is thinking it's an electrical issue and suggested wiring a direct 24V supply to solenoids 1,6 and 7 and seeing if it engages.

Would anyone have a suggestion of which way to go from here? Are either of us on the right track, or is there a better option?

Thanks!

 

[Nige]

That has all the hallmarks of a transmission control valve harness fault.
Serial Number.? How many hours.?
Is the TCV harness original.? Is the insulation on the wires hard and maybe cracked in places.?

We had active codes for intermittent/erratic signal from the transmission control/shift lever, as well as output speed sensor #1 erratic signal.

What Codes did you have when you first started.? Please list all of them.

I'm thinking a stuck modulation spool because it's also very harsh shifting when it does work, and the inching pedal doesn't have much response.

It would have to be all eight valves then because each clutch has its own modulation valve.

The TCV harness is #8 on this illustration. The one that is (or should be) zip-tied to the two steel "ladder racks" bolted to the control valve.

 

[Nige]

Sorry, re-read your OP and can see the S/N.
That machine was built in August 2002. If the TCV harness and the rear chassis harness (cab to TCV) are original one or other could well be the root of your problem.

Come up with some answers to the rest of the questions and we'll go from there.

There is an upgrade to the TCV on that machine. if it comes to the point of removing the the valve and disassembling it I am going to recommend that you do the upgrade. As far as parts are concerned it is 2 springs, 1 shim, & 1 spacer in one of the valve stations, so not a mountain of money involved. To set up the valve after rebuilding might well need a dozen or so 5J-1036 Shims.

I don't like the idea of putting 24v on three solenoid valves unless you either have the back of the machine up on axle stands, the rear wheels removed, or the output driveshaft between the tranny and the diff input removed.

 

[Sepult]

Hi Nige and Thanks for your help,

The TCV and chassis harnesses are original In the exposed sections of harness I haven't noticed any cracks. There are several visible locations on unrelated harnesses where repairs had been carried out in the past but I haven't found any locations on the TCV or chassis harnesses where repairs had taken place.

And yes, the diff shaft is disconnected.

The hours on the machine are around 7500.

When we first started we had the following active codes:
081 0585.02 Trans. output speed sensor #1 data erratic/incorrect
081 0673.02 Trans. output speed sensor #2 data erratic/incorrect
081 0668.02 Trans shift lever signal data erratic/incorrect

We also had the following stored/inactive codes:
081 1484.03 Inching pedal limit switch voltage above normal or shorted +

We did find trans. output speed sensor #1 was failed. The aluminum was completely eaten away. So we replaced both. And with relation to the 0668.02 code, we had the shift lever disassembled and the F/R switch inside was replaced. We had noticed that it was not reliably showing the forward gears when shifting, ie. it recognized 1R,2R,3R etc. but 1F,2F,3F etc. all showed N. Now after the repair we don't have that code or issue with the ECM recognizing the gear position.

Now we only get 081 0585.02, and it only goes active after the alarm goes off, so I'm assuming it's alarming out after the speed sensor on the output shaft doesn't send a signal.



So, going back over my notes and looking through SIS it seems we have a common fault for directional clutch packs 1, 2 and 3, since test ports for those clutches are not receiving pressure (except for the occasional time when it kicks in and starts working).

So my first assumption would be an issue with the inching pedal sensors or switches or wiring, since we had a code for the limit switch, and RENR5737-03 states the inching pedal only affects the pressure of the directional clutches. But we tested the NO and NC limit switch contacts at the ECM and they appeared to be operating fine, and we disconnected the inching pedal which had no effect, and even de-pinned the signal cable pin at the ECM and still no change.

So if it's a shared wiring issue in the output side, I guess it would probably be on the Solenoid Return 1 circuit, which is shared with solenoid 8.

So I can re-test the test port for solenoid 8/clutch 8. If it's pressure is 0, there's probably an issue in the return 1 circuit, which I can confirm by running a test jumper from the ECM to one of CP1,2 or 3 and check for operation. If the pressure is OK, maybe an intermittent issue with 3 signal wires suggesting probably a connector issue.

Does this sound reasonable, or would you suggest a different plan of action?

Thanks again!

 

[Sepult]

Update: I went to test clutch 8's pressure today during a rainstorm and found that it was working, and I had forward speeds 1,4,5,6 but not forward 2 or 3 or any reverse gear, and I didn't test 7 or 8 forward. I tried swapping in a backup ECM and behaviour was the same (except for calibration related codes since I didn't run calibration on the solenoids or inching pedal). So I'm thinking the harness makes the most sense

 

[Nige]

Update: I went to test clutch 8's pressure today during a rainstorm and found that it was working, and I had forward speeds 1,4,5,6 but not forward 2 or 3 or any reverse gear, and I didn't test 7 or 8 forward. I tried swapping in a backup ECM and behaviour was the same (except for calibration related codes since I didn't run calibration on the solenoids or inching pedal). So I'm thinking the harness makes the most sense

With symptoms like the ones you are describing it has to be electrical somewhere, of that I am pretty certain.

The chart below is clutch engagement for the various speeds.
There is nothing that is common between losing 2nd & 3rd speeds forward yet having 1, 4, 5, & 6.
In fact the speeds you did manage to "find" prove that ALL eight transmission clutches with the EXCEPTION of #3 (only used for reverse) were working at different times.

TBH I'd be looking at the transmission control that was "repaired" as well as wiring harnesses. As far as I'm aware that control is solid state and not repairable. Check the Part Number as well. If you have the former 161-1343 installed I would recommend that it be replaced with the newer P/N 180-3531.



Footnote: Regarding the 081 0585.02 Trans. output speed sensor #1 data erratic/incorrect the machine should work fine providing #2 sensor is giving a genuine signal. As you have removed the driveshaft then #1 Output Speed Sensor #1 ought to be giving a good signal if you can get the machine into any gear. Fix the other issues and the 585-02 Code might just well go away.

 

[Pep Joe]

Hi,
I've got a 140H S/N APM00296 that's got an intermittent, but almost constant now, issue with travel. We've lost all forward and reverse gears.

It was working when parked over winter. This summer when we started it we had no travel. We had active codes for intermittent/erratic signal from the transmission control/shift lever, as well as output speed sensor #1 erratic signal. We replaced the speed sensor, and the repaired the F/R switch in the shift lever. The speed sensor code still appears, although the wiring is OK from the ECU to the sensor. I'm assuming that this code is being caused by the ECU expecting there to be motion on the output shaft but there isn't, so it's throwing the code.

We're getting the correct pressure in every gear forward and reverse except for station A and B. They're 0 PSI. Except occasionally, we've gotten it to kick in and work perfectly and the pressure is normal and operation is normal, including shifting gears. Once it does it works until we shut down and allow it to sit. Then, same problem again.

I'm thinking a stuck modulation spool because it's also very harsh shifting when it does work, and the inching pedal doesn't have much response. So I was thinking of pulling the valve bank and inspecting. But an older, more experienced tech I know is thinking it's an electrical issue and suggested wiring a direct 24V supply to solenoids 1,6 and 7 and seeing if it engages.

Would anyone have a suggestion of which way to go from here? Are either of us on the right track, or is there a better option?

Thanks!

If you must power transmission solenoid with a battery for some testing, SIS recommended 12Vdc. Using 24Vdc will shorten the life span of the solenoids.

Try to monitor with ET the shift lever positions on ignition as you move the transmission control (shift lever) through all the forward and reverse gears to see if the shift lever control is shifting in all the gears respectively.

Since there is no fault codes relating to the transmission solenoids, I would be carrying out first the transmission control (shift lever) test as said above.

Did you say all the modulating valve pressures are ok? If yes what PSI you have in each one?

 

[Sepult]

Hi all,
Sorry for the delay in response, we've had other breakdowns and the grader has been on the back burner.

The control in this unit isn't solid state. I don't know if they changed anything later, but this one has a side plate that's removable and inside is an open wiper-style switch for 1,2,3,4,etc. and a toggle switch for F and R and I think there might be another switch for P. The wiper style one is actually adjustable so that 1,2,3, etc line up when the shifter is in the correct indentation, but if it were damaged I don't think it'd be repairable. However, the F/R is just a toggle switch and could probably be replaced with something similar. However, in our case, the electronics shop we use said our problem was just that it was gummed up and a bit of the glue holding the 2 halves together had broke free and worked it way down by the contact. I actually took a picture of it when they had it apart, but not of the whole mechanism.


It's hard to tell from the picture but there's a grain-of-rice size piece of green glue/epoxy? on the end there.

Anyway, after the repair ET is showing correctly all the gears in all positions so I don't think that's our problem now.

As for pressures, I went off RENR4104-12 in SIS for pressures in N, 1st, 2nd and 1st R and they were all within specs. I don't have the numbers here but I'll get them next week when I'm back at it.

It seems to me like it's got to be an issue in one of the harnesses, probably at a connector. So Monday or Tuesday I'm planning on starting at tracing that back.


Pep Joe thanks for that 12V suggestion, I was thinking a lower voltage might be a good idea and 12V should be like 50% PWM signal I'm assuming. I was thinking I might even bring over a potentiometer to wire in line so I can basically have a DIY inching pedal to prevent it from slamming into gear, although I guess that shouldn't be a problem with the shaft disconnected.


Thanks again everyone, I'll be sure to keep you updated on the progress!

 

[Nige]

I was thinking a lower voltage might be a good idea and 12V should be like 50% PWM signal I'm assuming.

Except for the fact that the feed to the solenoids isn't PWM......
They should still work on 12v though.

Should have made it a bit clearer about the transmission control. It is a rotary control with mechanical internal components but I still have my doubts as to whether it is repairable with any level of reliability. Maybe "sealed" would have been a better word to use to describe it.

I was wrong about the transmission control Part Number BTW. 180-3531 updates to 253-4019 which in turn updates to 452-9831 which finally updates to 585-0891. There have been a few issues with that control over the years I would say......

 

[Nige]

If you get to the point of changing them, here are the Part Numbers for the harnesses.
Transmission solenoid harness - 180-9324
Transmission RH frame harness - 169-3292 (It will not be cheap........)

As for pressures, I went off RENR4104-12 in SIS for pressures in N, 1st, 2nd and 1st R and they were all within specs. I don't have the numbers here but I'll get them next week when I'm back at it.

If the #7 (low range) clutch station on the transmission control valve has been updated the spec will be different. See Service Mag SEPD0937. The top pressure is allowed is 408psi, actual spec is 387 ± 21psi.

 

[Nige]

Here’s another random thought. When you are checking pressures you need all the machine’s systems at normal operating temperature. That means coolant above 80 DegC and transmission above at least 70 DegC. If you don’t do that it can produce some really screwy results.

 

[Sepult]

Except for the fact that the feed to the solenoids isn't PWM......

Yes it is. RENR5737-03 ECM operation:
"
The power train ECM responds to decisions by sending electrical signals through the various outputs. The outputs are pulse width modulated. The ECM operates the PWM outputs in an on/off manner or in a proportional manner. This depends on the requirements of the output device. The outputs create an action or the outputs provide information. The outputs are listed in the tables of Contact Descriptions.

"
I could monitor the duty cycle at the solenoids on my multimeter.

 

[Nige]

My apologies. I stand corrected.

If you were able to monitor duty cycle on the transmission solenoid supply were you also able to measure the voltage being supplied.?
Also what range of duty cycle measurements were you seeing.? Were they significantly different depending on which of the eight solenoids you were measuring.?

 

[Sepult]

Sorry for the late update:
So it turns out it wasn't electrical, per se. After chasing harnesses etc., we talked again to the operator who indicated the jumpy/erratic gear engagement was an ongoing issue for several years that he never reported. Draining the trans fluid again (after having changed it at the start of this process, and it having accumulated ~10h) the oil was contaminated with solids. We ended up pulling valves 1-2-3 and flushing the transmission through an external reservoir and replacing the valves with new units, after which it seemed to operate ok. But, obviously, that doesn't answer why there was so much crud in the oil. Pulling the transmission and disassembling we found the clutch for #1 and #3 to need replacing.

So we're assuming the dirt was plugging the valves, causing them to stick, and preventing proper shifting. This was probably preventable if the operator had notified someone when it first started happening.

Hopefully, this info will help someone in the future. Thanks to Nige and Pep Joe for the help, it was really appreciated!

 

[Nige]

Good update.

Did you go into the control valve while you had it apart.? There are orifices inside that unit that are prime candidates for getting plugged with debris and affecting shifting, possibly to the point of causing another clutch failure which I'm sure you don't want.

How did you go about setting pressures when you got it all back together.?