I think I may have the solution to the no audio issue. It seems that Apple CarPlay has THREE volumes. One for Siri, one for Navigation and the other for music or maybe that was Phone. Let's start with Siri. Do something to make Siri reply to you. Try to make it something that will make her talk for awhile. WHILE she is talking, turn up the volume on the radio. It must be exactly when she is talking. If you don't get it just right, you will be changing the radio volume, not Siri. Another suggestion is to adjust the volume controls on your phone. In navigation try the same thing. I have also read that there is a setting in Apple Maps for audio. The settings if I remember are: No Volume, low, medium and loud. Someone else solved their issue by resetting the phone while connected to Carplay. All this applies to Android Auto too. The problems I have been reading in this thread are issues across the board with many other brands. It is issues with Carplay and Android Auto. NOT isolated to our trucks. Do a web search about this and you will find pretty much the same. I used Siri no volume Carplay as my search terms. I don't have time right now to expound on this right now. Gotta run.