My old phone (Galaxy S7) worked perfectly with Ford Sync 3, so it’s not the car or a Sync3 issue. Both my phone and Sync 3 are fully updated.
With my OnePlus 7T, I cannot get Android Auto to work. The connection drops out (anywhere from 1 second to 1 minute).
On Sync3, you have to use USB tethering. OnePlus cable is being used, and several high quality and short length generic USB cables have been tested with the same issue.
When you plug in the USB cable, it opens Android Auto, but it always drops out. When opening USB preference and selecting anything other than "No Data Transfer", Android Auto drops out.
I’ve set Bluetooth tethering on and the default USB preferences to "File Transfer" (settings/system/developer options/default USB configuration).
I’ve done a factory reset with no backup transferred to my phone, and a factory reset on Sync 3. The same issues continue and I cannot use Android Auto for more than a few seconds before it drops out. When it does this, the Sync 3 doesn’t show Android Auto options to open, and my phone still has Android Auto running.
The problem is caused by the phone (One Plus 7T) defaulting my USB connection to "No data Transfer" even though I have it defaulted to "File Transfer". If I try to change it back to "File Transfer", it opens Android Auto for a second, and then drops out again, resetting it to "No Data Transfer". I can do this multiple times and every time it reset to "No Data Transfer".
How do I stop this and force it to stay on "File Transfer" so Android Auto can communicate with my phone?