D6T Transmission Fault When Calibrating

[PMW]

I’m sorry Nige. I gave you the incorrect code. It’s 672-2

 

[Nige]

I’m sorry Nige. I gave you the incorrect code. It’s 672-2

Converter output speed. I should have picked up on that from your previous post. See attached.

 

[PMW]

So I’m getting 147 ohms between the contacts. Seems out of spec. Guess I’ll have to get a sensor

 

[pittsburgh cat man]

I had a similar problem years ago I had a dozer that would come to instant stop in certain gears I could see on et it was engaging 3 clutch’s in transmission packs in transmission turned out to be a bad position sensor on transmission control that’s just a thought that pops up in my head I think if Nige roots around a little there is a service mag on position sensors one last thought if drive shaft isn’t turning I don’t think you would have a signal from torque output sensor

 

[Nige]

one last thought if drive shaft isn’t turning I don’t think you would have a signal from torque output sensor

I think he has ET. It might be worth monitoring the signal from the TC output sensor when the shaft is spinning in neutral.

turned out to be a bad position sensor on transmission control that’s just a thought that pops up in my head

I had a quick look under LAY-prefix for this machine and nothing popped up. Need to dig deeper....
EDIT: Found it. It was for D6N tractors, so a fair way prior to the 6T.

 

[tctractors]

You will need a little mirror on a stem and a tippex pen to set the sensor on the correct tooth contact space, the spec' is half a turn up from the tooth, I tend to go a bit higher to near 3/4 of a turn up off the tooth and lock them in place, be very careful of falling dirt as the sensor area is often well buried in crap.

 

[PMW]

It might be worth monitoring the signal from the TC output sensor when the shaft is spinning in neutral

Ok. So the shaft doesn’t spin long in neutral at all but for the short time it does, it doesn’t show torque converter rpm.

But a question I’ve asked a few local guys without getting an answer, is the code popping up because the shaft isn’t spinning or can a faulty speed sensor cause it to not spin? Local cat dealer thinks I’m focusing to much on the electrical when it’s probably mechanical prob in the tc.

 

[Nige]

But a question I’ve asked a few local guys without getting an answer, is the code popping up because the shaft isn’t spinning or can a faulty speed sensor cause it to not spin?

If you look at it with ET AFAIK the sensor should register a zero RPM reading when the shaft is not spinning. FMI02 is "erratic, internmittent, or incorrect" data. Are you seeing a wildly varying TC Out Speed value (for example) at Low Idle when the engine RPM should be somewhat stable.?

If the TC Out speed sensor is faulting then IMHO that issue should be addressed first before moving on. It's what diagnostics are all about.

Have you gone through all steps 2-4 troubleshooting procedure after you found the sensor resistance was out of spec to check the wiring.?

Local cat dealer thinks I’m focusing to much on the electrical when it’s probably mechanical prob in the cv.

That may turn out to be the case at the end of the day but, again IMHO, you need all the external factors corrected before condemning the transmission as somehow defective internally. You'd be kicking yourself for pulling a transmission that after removal was found to be operating correctly.

Have you had pressure gauges on it yet.? I would suggest putting gauges on all five clutches at the same time so that you can get a good idea what is happening to all the clutches (not just the two that are supposed to be engaged) when any specific transmission speed is selected.

 

[pittsburgh cat man]

Cat speed sensors make a very small amount of ac current by reading the teeth passing the sensor I have seen them ground off by the gear seeing it turns in nuetral I don't think it would or could possibly stop the torque like Nige just said put gages on all 5 clutches look for more than two engaged at any gear nuetral will prob only have one

 

[PMW]

If you look at it with ET AFAIK the sensor should register a zero RPM reading when the shaft is not spinning. FMI02 is "erratic, internmittent, or incorrect" data. Are you seeing a wildly varying TC Out Speed value (for example) at Low Idle when the engine RPM should be somewhat stable.?

in ET it shows 0 rpm even the short period that’s it’s spinning initially at startup. So yes, there could be something up with sensor… but they’re telling me that shaft should always spin if the engine is running. If not, then in their opinion it’s either mechanical in the torque converter or pressure not getting to the torque converter or bypassing inside. They don’t think it’s something to do with transmission anymore

 

[Nige]

[QUOTE="PMW, post: 1285575, member: 220183]but they’re telling me that shaft should always spin if the engine is running.[/QUOTE]
Remember that the value being measured is TC OUT speed, so something must be happening inside the converter to spin the shaft in neutral.

I know it might be hard to quantify but do you reckon the shaft is spinning at give or take about engine RPM when the engine is idling.?

What, even if the transmission is in gear.? Sorry that’s BS. Engage any gear at engine Low Idle RPM and that shaft should stop dead.

Who are “they” BTW.?

 

[pittsburgh cat man]

I'm sorry I disagree with that if you are in nuetral and engine is running yes it will spin but if you put transmission in gear at low idle it will not it will also not turn when there is enough load on it to make stall speed you can see that at 3rd gear stall

 

[Mobiltech]

If the shaft is not spinning in neutral either there is a torque problem or the trans is locking up somehow. The speed sensor has nothing to do with this.
I am betting you have something wrong in the torque.
If you rev the engine to full speed in neutral what is the rpm at. If it’s going to full rpm and not torque stall speed then you have a torque converter issue.

 

[pittsburgh cat man]

I went back and read all the posts. Burning all the speed packs out and putting a lot of load on it in reverse concerns me. I think prob is in what it is telling tran what to do need to check pressures in all gear combinations

 

[PMW]

Got it going! Not sure how or why but my helper accidentally pressed high idle buttton while in fwd and going through gears while I was checking pressures in back. We were through all the gears. Pressures all seemed to be at spec. But after he pressed that button off she went. I’ve since calibrated again, gone trough all gears in fwd and rev and I all seems to work as it should. Make of that what you will….

If you rev the engine to full speed in neutral what is the rpm at.

I didn’t read these last 3 msg from you guys till now so didn’t actually get a chance to look but speed sensor was reading as well

What, even if the transmission is in gear.? Sorry that’s BS. Engage any gear at engine Low Idle RPM and that shaft should stop dead.

I was speaking to it being in neutral then it should always turn…

 

[Nige]

Great news...!! Pleased for you because it's been a long road.
Did you fill the tranny with the TO-4 oil in (Petro Canada.?) it that we talked about a few pages back.?

Next suggestions. 50 hours on the tranny, change the filter and do a filter cut. Inspect for particles.
Throw the gauges on it again if you feel inclined/have the time.
Do you do oil sampling at your company.?

 

[PMW]

Did you fill the tranny with the TO-4 oil in (Petro Canada.?)

Yes I did fill with this oil

Next suggestions. 50 hours on the tranny, change the filter and do a filter cut. Inspect for particles.
Throw the gauges on it again if you feel inclined/have the time.
Do you do oil sampling at your company.?

I intended to change it after a bit of use so I will also cut it as well. But no, we don’t do oil sampling typically.

 

[Nige]

Yes I did fill with this oil

I intended to change it after a bit of use so I will also cut it as well. But no, we don’t do oil sampling typically.

If you did oil sampling you could do a filter change + cut and take an oil sample. No need to change the fluid unless in the highly unlikely event that the oil was somehow contaminated. Think about it with respect to cost and time.......

I forget where we were now but what did you do regarding the transmission pump and the cooler.?

 

[PMW]

what did you do regarding the transmission pump and the cooler.?

We didn’t touch the pump seeing the initial pressures were ok, and no we didn’t bother with cooler either.


Thanks to everyone who helped along the way. Really appreciate it!