Communication and Hosted Diagnostics
WARNING: This page is about a different car, the 2019 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
The 14 V power module has no internal diagnostic tests and does not communicate over serial data. The engine control module (ECM) monitors and controls the 14 V power module and will report DTCs if a fault is detected.