2009 HD Transmission codes

I have been experiencing an issue with the transmission throwing the code P0741 (Torque Converter stuck off) when pulling my stock trailer. When the service engine light comes on, the transmission will not shift into 6th gear and the converter seems to stop working. At highway speeds, the engine rpm's vary and the shift points are prolonged and of course the fuel mileage drops to about 6-7 mpg at this point. This happens every time I pull a heavy load.(Trailer weighs 6,000lbs) When I stop and turn the truck off, the system seems to reset and the transmission will shift fine for a couple of miles and sometimes it will happen again immediately. I have taken it to the dealer for this issue too many times to count and they cannot replicate the concern so they clear the codes and send me on my way. They did replace the TCM and another part (something to do with the valve body I think, Not sure what without looking it up) but this hasn't done anything to fix the problem. This started happening while the truck was still under the GM powertrain warranty and has continued past the GM coverage and the extended warranty I purchased has been covering the visits to the dealer since. Currently I'm at 125,000 miles with up to date service records, all of which have been when GM recommends them, and this problem is still haunting me. Anyone else having this problem? Anyone heard of this happening?

I have been experiencing an issue with the transmission throwing the code P0741 (Torque Converter stuck off) when pulling my stock trailer. When the service engine light comes on, the transmission will not shift into 6th gear and the converter seems to stop working. At highway speeds, the engine rpm's vary and the shift points are prolonged and of course the fuel mileage drops to about 6-7 mpg at this point. This happens every time I pull a heavy load.(Trailer weighs 6,000lbs) When I stop and turn the truck off, the system seems to reset and the transmission will shift fine for a couple of miles and sometimes it will happen again immediately. I have taken it to the dealer for this issue too many times to count and they cannot replicate the concern so they clear the codes and send me on my way. They did replace the TCM and another part (something to do with the valve body I think, Not sure what without looking it up) but this hasn't done anything to fix the problem. This started happening while the truck was still under the GM powertrain warranty and has continued past the GM coverage and the extended warranty I purchased has been covering the visits to the dealer since. Currently I'm at 125,000 miles with up to date service records, all of which have been when GM recommends them, and this problem is still haunting me. Anyone else having this problem? Anyone heard of this happening?

when towing or hauling the use of 4th gear with 4sp or 6th with 6sp should not be used. torque converter should be off when towing.reason the PCM shuts off the torque converter is high temps.