I am having issues with Apple CarPlay in my SYNC 3 equipped vehicle
Apple CarPlay is very picky about its connection to SYNC 3. Most issues with Apple CarPlay can be solved by replacing the USB cable used to connect your device to your SYNC 3 system. You should always use a Genuine Apple Lightning cable that is in excellent shape. Some off brand and well used cables will cause an array of "flaky" issues and make your CarPlay experience a poor one.
If this does not resolve your issue, try:
-Resetting your phone
-Master resetting SYNC 3
-Re-seating your USB connections behind the dash
-Ensuring the rings around the USB ports are "lit" (indicating there is power)
-Ensuring another device such as a phone or thumb drive will communicate with the SYNC system when plugged in