A hypothesis: There exists a Bluetooth 5.3 connection error isolated to iPhone 15 Pro and Pro Max models running the A17 Pro chip causing disconnectiom issues in older models of cars.
My summary: iPhone 14 or iPhone 15 connects in older vehicles, so there should be no reason why the iPhone 15 Pro and iPhone 15 Pro Max shouldn't work, unless there is a hardware, software or firmware issue specific to these more advanced models using the A17 Pro chipset.
Apologies, I get a bit geeky here so pass by if you don't do tech ...
My observations:
- My iPhone 15 Pro on iOS 17.2.1 repeatedly disconnects at exactly 40 seconds in my 2013 Audi A4.
- This problem has persisted through various iOS updates since purchasing my iPhone 15 Pro.
- A number of posts in this thread highlight problems with iPhone 15 Pro or iPhone Pro Max and either older Audi, Porsche or VW cars.
- I have tested my iPhone 15 Pro in a 2019 VW Polo and there are NO disconnection issues.
- A number of posts highlight no problems with older phones.
- I have tested my car setup with an iPhone XR, iPhone 14 and iPhone 15, all running iOS 17.2.1 and in my experience, there are NO disconnection problems.
- Phone 15 Pro and iPhone 15 Pro Max use the new A17 Pro chip, whereas the iPhone 14 and 15 tested in Point above use the A16 chip.
- A16 and A17 Pro chips both support Bluetooth 5.3.
The common factors for me are:
- Older vehicles
- 15 Pro and Pro Max
- A17 Pro chip
A bit of research around Point 1 (disconnection at 40 seconds), Point 7 (Bluetooth 5.3) and the Bluetooth Organisation,led me to Bluetooth 5.3 Core Specification Volume 6 Part B Section 5.2 which states:
"If the procedure response timeout timer reaches 40 seconds, the ACL
connection is considered lost (see Section 4.5.12). The Link Layer exits the
Connection state and shall transition to the Standby state. The Host shall be
notified of the loss of connection."
This refers to termination of a bluetooth connection between two devices.
Does this seem like a coincidence?
I wonder if older cars are using the low data rate Bluetooth connections eg. BLE, whereas modern cars are using A2DP which supports streaming i.e. data transfer. This should not be a problem though ...
A wider search of bluetooth disconnection issues on other devices ranging from tablets, PCs, airpods and cars all point to this 40 second benchmark. This is not a new phenomena isolated to these phones and our cars, it should be a straightforward software fix for Apple to render successfully.