Transmission P1818 code after tuning

I had a friend who swapped his 2008 GMC 5.3 to a 6.0 retaining the 4l60. We tuned the engine to get it running and had to sort out several misfire issues as well as some wiring issues from backyard repairs. The truck ran for about 250 miles and then started throwing P1818 codes. He had a local shop rebuild the transmission and they stated that it was burned up from slippage. They rebuilt it and it still continues to throw a P1818 code. A P1818 DTC means the TFP manual valve switch thinks that Drive is selected, but the ECU sees a different gear. As I am not that versed in GM platforms, would someone with some experience please consider taking a look at the tune file and see if there is something I have missed that may be causing this issue?




Thank you for the help!