P0688 P2112 P126E Fault Diagnosis for 2006 Ram 2500 5.7 Hemi After Engine Replacement

I recently installed a new engine in my 2006 Ram 2500 5.7L Hemi, but now the truck will crank but not start. The onboard diagnostic system is showing codes P0688, P2112, and P126E. Prior to this, the vehicle had been sitting for over a year and was running normally until recently. I've already replaced the battery, ordered a new TIPM (Terminal Interface Power Module) from O'Reilly's, installed new terminals, and tested all connections both when cranking and when parked. Voltage readings show 12.3V when parked and drop to 11.4V during cranking. Despite these efforts, the truck still fails to start. I'm seeking advice on how to properly diagnose and resolve this issue. Any insights or troubleshooting steps would be greatly appreciated. Thank you.