Issue: The vehicle's touchscreen display is illuminated / on but is experiencing "ghost-touch" or no-touch response.
Explanation (Internal Use Only): The display digitizer has failed. A very common problem with GM vehicles equipped with the 8-inch touchscreen display. When the customer or installer removes & replaces the touchscreen it is recommended that they remove the cables with ease. Although rare, older vehicles that experience extreme climate cycles could have a fragile video cable. If it becomes damaged, they can purchase a replacement from their local dealer. Part Number 84022314.
Resolution: The touchscreen display needs to be replaced or serviced by Infotainment.
Issue: The vehicle's touchscreen display is not illuminated / off when the vehicle is running. The touchscreen display will not illuminate.
Explanation (Internal Use Only): The vehicle is experiencing a CAN-bus related issue. Specifically related to the MOST Bus (Media Oriented Systems Transport). This is a prevalent problem with late-model GM vehicles. If any module on the MOST Bus fails or if there is a short/open, the touchscreen display will go black. Please note, in excess of a black screen the customer may also need a replacement touchscreen display if experiencing any of the symptoms listed in that repair service.
Resolution: The vehicle will need to be diagnosed by a local GM dealer or qualified mechanic to read the vehicle's DTC codes and/or run the "MOST Bus diagnostic test.". This will pinpoint the troubled module which will need to be replaced with a pre-programmed replacement unit by Infotainment.
Below is the likelihood of the troubled module within the MOST Bus circuit based on history:
Human Machine Interface (HMI): 60%
Audio Control Module (ACM): 25%
Instrument Panel Cluster (IPC): <5%
Disc Player: <5%
Amplifier: <5%
Display not showing but rear camera does in a GM vehicle
This is more than likely caused by a faulty HMI module, however if the cx also reports no sound functions, refer them to their local dealer to have a MOST-bus diagnostic run on the vehicle.