I don't know if this is an android auto problem, or an android 14 (crdroid 10) problem. Wired usb connection. Have tried different cables with same effect. I did not have this problem before (Android 13). My phone has AA 10.9.634644.
If the phone is locked when connecting to the car, I get a connect/disconnect loop. This continues until I unlock the phone, and then things are fine after a few seconds, and I can then lock the phone again.
If I connect to the car with the phone unlocked until AA connects, and then lock the phone, everything is fine.
I have android auto configured to connect with the phone locked, and have disabled USB debugging.
Don't rule out the wire behind the dash. I was experiencing similar behavior until my phone just didn't connect but still was getting power from the port. Turns out the wire connecting the USB port and the head unit was faulty. If I wiggled the wire on the end connected to the head unit then it worked like normal.