Took first road trip (~150 miles) today since it was for fixed second time on December 22 and about 100 miles into trip pre-collision assist and cruise control shut off again. Ugh. Almost becoming funny. Rest of car is great.
They said before they lost communication with the module. Sounds like they need to check the CAN communication wiring from the module to the first CAN block it connects to and also the power and grounds. Communication wires shut down, it looses communication. Power or grounds disconnected, it looses communication.
Here is how I would approach the issue.
Connect scan tool and keep and see if I can communicate.
Once connected to the module go into the section where you can read values such as the distance the sensor is currently reading.
While its doing this wiggle the wiring harness in various spots. When the readings go crazy or the module drops communication you have found the problem area.
Since this is a brand new vehicle it sounds to me like a harness issue. Pinched wire, broken wire in the insulation, spread terminal, or softset connection.
EDIT:
Well after looking at the diagrams of the network topology (From a 2012 model, which should be pretty close to a 2016 facelift), it probably won't be the CAN lines.
From the OBD-II port the CAN lines piggy back off each module and joint connector with the PCM being at the very end of these runs. Right before the PCM the Cruise control module is the last node.
If one of these CAN wires shorted or had an open circuit, I think your vehicle would throw an ungodly amount of errors since every module just lost communication with the PCM.
This really leaves power/ground issues in my opinion.
