6L90 codes

[CheezWhiz]

2016 silverado 2500HD 6.0 vortec, 120k miles Pretty light usage, daily driver, no towing. Did a few fluid exchanges with a pump but never changed the filter. Seems to sometimes exhibit delayed shifts into fourth gear, like needs to be at a higher RPM than it should need to be to upshift from third to fourth.

Was throwing a P0700 and P0741 code so I took to a local transmission shop. The shop dropped the pan and said that there was very little debris and the fluid and filter actually look pretty good. But they are sure I need a converter. They said they would use a heavy duty billet converter from Precision in New Hampshire. They are going to take a look at the pump and the 4-5-6 clutch and let me know what they think.

Any advice going forward with this situation? If the pump and 4-5-6 clutch looks good, it is tempting to just replace the converter vs paying for a full rebuild, especially considering that the fluid looked good with very little debris in the pan. But maybe that's wishful thinking?

 

[clinebarger]

I would drop the Valve Body /TEHCM assembly & mechanically test the TCC Solenoid for proper operation FIRST. Requires a test plate that not every shop has.
Next is vacuum testing the TCC Regulator Valve & making sure the valve is free.

If the above checks out.....The Converter needs to be cut open to verify that the clutch lining has failed, I'm fortunate to have a good converter shop local, This shop obviously doesn't to have converters shipped across the country.

Converter clutch lining failure sheds debris 99% of the time....Unless you caught it extremely early!!

Shops do things different ways, And I don't want to assume this is the old (Let's sale them this....If that doesn't fix it, Then we will diagnose the issue)

 

[CheezWhiz]

2016 silverado 2500HD 6.0 vortec, 120k miles Pretty light usage, daily driver, no towing. Did a few fluid exchanges with a pump but never changed the filter. Seems to sometimes exhibit delayed shifts into fourth gear, like needs to be at a higher RPM than it should need to be to upshift from third to fourth.

Was throwing a P0700 and P0741 code so I took to a local transmission shop. The shop dropped the pan and said that there was very little debris and the fluid and filter actually look pretty good. But they are sure I need a converter. They said they would use a heavy duty billet converter from Precision in New Hampshire. They are going to take a look at the pump and the 4-5-6 clutch and let me know what they think.

Any advice going forward with this situation? If the pump and 4-5-6 clutch looks good, it is tempting to just replace the converter vs paying for a full rebuild, especially considering that the fluid looked good with very little debris in the pan. But maybe that's wishful thinking?

sorry new hampton iowa, not new hampshire.

 

[CheezWhiz]

I would drop the Valve Body /TEHCM assembly & mechanically test the TCC Solenoid for proper operation FIRST. Requires a test plate that not every shop has.
Next is vacuum testing the TCC Regulator Valve & making sure the valve is free.

If the above checks out.....The Converter needs to be cut open to verify that the clutch lining has failed, I'm fortunate to have a good converter shop local, This shop obviously doesn't to have converters shipped across the country.

Converter clutch lining failure sheds debris 99% of the time....Unless you caught it extremely early!!

Shops do things different ways, And I don't want to assume this is the old (Let's sale them this....If that doesn't fix it, Then we will diagnose the issue)

I can't say for sure they did the diagnostic checks you suggest, I just know they have really strong reviews and seem confident the converter is shot. I guess if the solenoid or valve was the issue then replacing the converter wouldn't fix the problem though, so it should be obvious enough when I get it back if they misdiagnosed it. I don't get the impression they are trying to milk me for $ since at first the guy was leaning toward a complete rebuild and seems to have backed off from that quite a bit after getting a look inside the pan.

is there any reason that just a TCC would cause the 3-4 upshift to occur at higher RPM? Or does that necessarily mean that the 4-5-6 clutch is shot?

 

[clinebarger]

Like I said....Didn't want to assume anything.

P0741 freezes shift adaptation so it would be tough to say anything is wrong with the 4-5-6 clutch as the TEHCM learned the 3-4 shift while the TCC was in play.

Of course....The 4-5-6, 3-5-R, 2-6 & 1-2-3-4 clutches should be checked if the bellhousing/pump is pulled, Only takes a few minutes at that point.

 

[Snagglefoot]

No expert at all, but once they pull the transmission to get at the torque converter, and considering it’s not unusual for the converter to pile up at 120,000 miles, I’d have them do the billet convertor, inspect the rest and replace the clutch material which essentially is a rebuild. I have 269,000 miles on mine, no codes, but have a delay in reverse. I’m thinking of the same thing.

 

[CheezWhiz]

there isn't much else wrong with the truck, the 6.0 iron block has a reputation for longevity. those factors weigh in favor of just biting the bullet and going through the trans completely.

on the other hand, i work from home and we just bought a 2025 tahoe, so the truck will be retired from daily driver usage. assuming i can get away with just just replacing the converter, that might get me another 10 years and 50k miles. at which point i will probably inherit the tahoe and owe the wife another upgrade