Was this truck in a flood or an accident? It looks like the BCM has gone out, but I would start by checking all fuses with the systems on. This guide can help:
https://www.2carpros.com/articles/how-to-check-a-car-fuse
The U0422 code in a 2017 GMC Sierra indicates a problem with the "Invalid Data Received from Body Control Module" or BCP (Body Control Module "B").
The U0401 code is a generic diagnostic trouble code (DTC) that indicates a communication problem between the Engine Control Module (ECM) and the Transmission Control Module (TCM)
Here are the fuse locations so you check run the test and I have included how to change the BCM out as well, you can get a preprogrammed unit by searching Google or Ebay. Check out the images (below). Please let us know how it goes.
Images (Click to make bigger)
Monday, August 14th, 2023 AT 12:17 PM