The first thing that I think of is the totally integrated power module. The pins in the connectors are often an issue. If you had things disconnected, that is where I would check first. Make sure we don't have a bent, corroded, or pushed-in pin.
As far as the schematics are concerned, I attached the communication data line schematic below. See pics 1 and 2. The remaining pics are specific to the U0168. I'm somewhat confident that is where the problem lies.
When you look through the diagnostics, note that the communication from the WCM is done over the can B circuit. The PCM is connected to the can C circuit via the TIPM. That is why I'm suggesting starting there.
Additionally, I attached the diagnostics specific to this code as well.
Let me know if this helps and what you find.
See pics below.
Images (Click to enlarge)
Thursday, November 24th, 2022 AT 9:51 PM