So I have been having this issue for over a month, When i plug in my phone the volume on the radio drops and i can only adjust notification volume. It will automatically switch back and forth about every 30 seconds. I have had some rare cases where it doesn't happen but 99.9% of the time it is an issue. The only thing I can come up with is Android Auto is sending constant notification to the truck which is causing it to volume to drop every 30 seconds. It doesn't matter what is running maps, pandora, regular radio as soon as Android Auto connects it happens
PLEASE SOMEONE HELP I AM GOING INSANE.

 

Unistall and reinstall Android Auto.

 

That didnt solve the problem

 

Try a different cable? I dunno. I find android auto useless myself.

 

Had this on a truck I took off the lot to drive over the weekend. Annoying no doubt. I tried a few things too, no fix that I found.