@NickTransmissions is a member here with great knowledge of these transmissions. Perhaps he'll offer some advice.

 

Did it exhibit these low-speed symptoms prior to the rebuild?

It is very hard to pinpoint issues post-rebuild unless the drivability symptoms are so blindingly obvious that even school children can tell you what's wrong with the transmission. That said, I'd want to know the following:

1. Was the TEHCM replaced?
2. Do you have a new or remanufactured pump assembly, including a new gasket between the stator and stator support?
3. Was the valve body vac-tested?
   • The Sonnax Zip kit is a great kit, I use it all the time and usually fixes most worn valve bodies
4. What were the clutch clearances for the two packs in that 3-5-R drum?
5. What frictions did they use (If OEM that may be enough to explain your problems as those were all engineered to run with Dex VI)?
6. What tune did they use and did the tune delete TCC lock up during speeds 2-4?

You may not even have a transmission or torque converter problem but need a lot more info/data to even begin pin-pointing anything.

• Did you contact the shop that built it - if so what did they say?

• Did any of the other shops who looked at it take it for a test drive with the bi-direction scan tool plugged in and live engine, transmission and torque converter displayed on the screen?
  • If no, why not?
    • That would have been the first thing I would have done
    • Codes are fine if present but sometimes the system adapts enough to avoid the thresholds required to set/store a DTC but doesn't mean you don't have a problem....

 

Did it exhibit these low-speed symptoms prior to the rebuild?

It is very hard to pinpoint issues post-rebuild unless the drivability symptoms are so blindingly obvious that even school children can tell you what's wrong with the transmission. That said, I'd want to know the following:

1. Was the TEHCM replaced?
2. Do you have a new or remanufactured pump assembly, including a new gasket between the stator and stator support?
3. Was the valve body vac-tested?
   • The Sonnax Zip kit is a great kit, I use it all the time and usually fixes most worn valve bodies
4. What were the clutch clearances for the two packs in that 3-5-R drum?
5. What frictions did they use (If OEM that may be enough to explain your problems as those were all engineered to run with Dex VI)?
6. What tune did they use and did the tune delete TCC lock up during speeds 2-4?

You may not even have a transmission or torque converter problem but need a lot more info/data to even begin pin-pointing anything.

• Did you contact the shop that built it - if so what did they say?

• Did any of the other shops who looked at it take it for a test drive with the bi-direction scan tool plugged in and live engine, transmission and torque converter displayed on the screen?
  • If no, why not?
    • That would have been the first thing I would have done
    • Codes are fine if present but sometimes the system adapts enough to avoid the thresholds required to set/store a DTC but doesn't mean you don't have a problem....

Nick,
I will copy and paste here what was performed. I contacted the shop who did it shortly after getting it back and they told me that I’d have to bring it back for them to diagnose. They told me they used HPTuners to tune the trans, but couldn’t tell me what tune. They just said they use the same tune on all of the 6L90Es. I haven’t taken it back yet because the shop is 200 miles away and I have to coordinate with friends and my work schedule to do it. I took it for scan/ diagnosis at other mechanic shops hoping that if it did in fact point to the transmission or torque converter, then I wouldn’t be wasting time, lost work hours, and money taking it back.As far as how the shops scanned it and what they used, I can’t honestly say. Both did tell me they were looking at live data and that everything seems to be doing what it is suppose to be doing when it’s suppose to.
Here is the message from the shop before I took it for repair:

“Got your inquiry from our website, thank you for reaching out again. You would be looking at $3550 installed, yes. As far as parts go, we use factory Borg frictions and steels (including one extra friction in 35R and 456), Sonnax zip kit, machined bellhousing and pump stator, new GM rotor and vane kit (we measure pump pocket depth to ensure the correct out of three rotor sizes is used), weld the 35R/ 1234 drum, Sonnax 1234 piston, hyperblue molded pistons and a billet piston single disc torque converter. We also reflash the transmission once it is reinstalled in the truck to modify the lockup schedule. A two year/ unlimited mile workmanship warranty is also given with the build. With the P0741 code you had listed, we probably would encourage not driving it up here if at all possible, so you are on the right track with thinking of having it towed here. If you have any other questions please feel free to let us know. Have a good weekend!

Thank you,”

 

First I've heard anyone post that dex6 is hard on seals... I've heard it can leak when used in parts not designed for it, as the seals have to be changed a bit (ie, older stuff not designed for dex iv).

Your '02 originally would have used DexIII, and using it will be fine..

 

Here is the reply from the shop on the questions you had me ask:

“Good morning, sorry to hear you are experiencing some issues. The other transmission guy is correct, best thing to do is going to be bring it back to us. To address a few of your questions though, the techm was not replaced. It’s not a normal thing to be replaced if there are no hard solenoid codes present. It had new discs for the pressure pad installed, along with new seals to seal it to the valve body. This is pretty much the standard, as a techm is rarely ever bad, maybe one out of a hundred, and we’ve yet to have one bad here.

The bell and stator are machined or new just depends what we have at the time, regardless, not reused as the converter kills the surface of it when it comes apart. Rotor and slide clearance is measured to ensure proper clearance. Gasket is replaced between stator, but not with the kind that has silicone as they are prone to have issues. A normal factory style paper gasket is what we use.

The valve body has a zip kit installed, which addresses all known internal issues.

We use Borg frictions.

And finally, we used Hptuners to turn off tcc in lower gears. What you are experiencing may be something as simple as needing to raise shift points higher, it could just be going into too high of a gear at low speeds. Logan will ride along with you if/ when you bring it up so he can see exactly what’s going on me.

Also, it’s worth noting that vacuum testing is not always an accurate was of testing bore quality, as some bores will have worse vacuum reading if valve are changed as replacement valves are designed to self clean.
If you need anything else or would like to schedule a time to get it back up here to us, please let me know.”

Part 2:
“We have put dex3 in 100+ 6L transmissions from stock to 1000whp with no issue. Dex6 is hard on seals in any transmission its installed in hence why we do not use it in these applications. Some of the 8sp and 10sp we would use different stuff but definitely not any 6L transmission

If it has a small flare at light throttle I can adjust it and fix it via tuning- it’s as simple as changing shift timing and oncoming pressure. I feel like I would have addressed it when it was here but maybe i wasnt as light of throttle we are in the country here and i just drive up to speed normal. Non then less, we have a ton of tunability with these transmissions to take care of things like that. “

Gotcha...I always replace the TEHCM, IMS and Harness/Speed Sensor assembly so those three things by themselves account for the difference in pricing, at least insofar as the cost of the transmission rebuild itself. Some builders prefer not to replace for the reasons they provided but I'd rather be safe than sorry. Plus I won't warranty a 6L job if the customer elects not to replace the TEHCM, IMS or sensors/harness.

At this point, I'd let them take it from here...Glad they are responsive and seem to want to get it fixed for you...

First I've heard anyone post that dex6 is hard on seals...

Same - I've never heard anyone in the industry mention that before. Figure the some of these transmissions come in with over 200k on the clock so it can't be too hard on them (and when they say 'seals', im assuming they're referring to the sealing surfaces on the lip seals on the apply and balance pistons/piston dams).

 

Sorry, it’s been a few days since I replied. I’m still trying to get things lined up to take the truck back to the transmission shop. In the meantime, the “Service Stabilitrak” message came up again in the DIC again and went off after a second or 3. Yesterday the truck ran like total crap…like it was in reduced power mode or something. When it does this, it feels like you’re pulling 10,000 pounds behind it. I started researching and keep coming across articles about ground wires in the dash, the passenger side fender well, and connections at the fuse boxes under the hood. I’m going to check those things when time permits. The shift flares are becoming more noticeable and frequent too. They’re not always just on the first drive of the day anymore. The miss/stutter I’ve been feeling/noticing isn’t always at low speed/low rpm either…yesterday it did it while cruising at 50-55MPH on the highway.

I looked back through the last scan on the truck I did with a snap on scan tool and saw these…B1325 Control module power circuit voltage below threshold and U0164 Lost communication with HVAC control module. Not sure if these were stored from the time when the truck was scanned last winter or the recent scan I did.

 

Sorry, it’s been a few days since I replied. I’m still trying to get things lined up to take the truck back to the transmission shop. In the meantime, the “Service Stabilitrak” message came up again in the DIC again and went off after a second or 3. Yesterday the truck ran like total crap…like it was in reduced power mode or something. When it does this, it feels like you’re pulling 10,000 pounds behind it. I started researching and keep coming across articles about ground wires in the dash, the passenger side fender well, and connections at the fuse boxes under the hood. I’m going to check those things when time permits. The shift flares are becoming more noticeable and frequent too. They’re not always just on the first drive of the day anymore. The miss/stutter I’ve been feeling/noticing isn’t always at low speed/low rpm either…yesterday it did it while cruising at 50-55MPH on the highway.

I looked back through the last scan on the truck I did with a snap on scan tool and saw these…B1325 Control module power circuit voltage below threshold and U0164 Lost communication with HVAC control module. Not sure if these were stored from the time when the truck was scanned last winter or the recent scan I did.

I'd stop driving the truck at this point, otherwise you risk doing damage to other things beyond the transmission.

Also, ask the transmission shop if they reinforced the welds on the 3-5-R drum...2-3 shift flaring is has it's root cause in a leaking drum, which results in apply pressure loss to that clutch, resulting in burn-up over time. Symptoms usually start on the 2-3 shift then progress to flaring from 4-5 and delayed engagements/slippage in reverse...