This isn't rocket science, especially if the fault is there all the time. It is a circuit fault. It can only be one of two wires going from the TCM to the Solenoid in the transmission. They have replaced the TCM and the solenoid? That only leaves the wiring. So I'm back to replacing the terminals for the TCM side for the two circuits, then replace the same two wires from TCM to transmission connector. That only leaves the transmission pins, which can also be replaced with 68228245AA which is $337. There is no need to replace a complete harness. It usually results in collateral damage because the harness is put in as the truck is built, and can be very difficult to replace in the truck.