Pumbah

I have a 2003 Chevy silverado, having an issue with the transmission 4L60e after the engine harness was swapped completely trying to resolve other issues it had before, 1st gear and 2nd work fine but it won’t shift to 3rd and it’s giving me codes P0740 P0785, solenoids seem to be working fine, also checked fuses, any idea what I should check next before switching the transmission harness? TIA...... FYI Code U107 has been fixed it was the TAC Module .