I tried to read the Diagnostic Trouble Code with the DashDAQ, but I get an error "Please Wait"

More than likely you have a corrupt file on the sd card, and it may have to be reformatted. Before you do this, make sure all your files are backed up from the sd card, and then copied to your computer.

You can reformat the SD NAV card without any problems. The maps reside on a different partition and you would need a Linux PC to change anything there.