Ok so I think I figured this out, and why some cables and cars work and some do not. I have 3 cars, 1 worked but inconsistently dropped out, two did not. This was using the Apple supplied USB-C cable and a USB-A to USB-C adapter I have had for years from Sabrient.
This is fundamentally a USB power delivery configuration issue that puts the phone into a Power delivery mode that the USB Host will not support. Cable's impact this because the USB-A to USB-C converters are not consistent.
I purchased the following cables, and received them in the mail yesterday and it resolved my issues across all my vehicles:
https://www.amazon.com/dp/B0BY1HMKPR?psc=1&ref=ppx_yo2ov_dt_b_product_details
The problem occurs due to the implmentation of the USB-A to USB-C conversion. The following control lines exist on USB-C.
USB-A is much simpler and only has the following:
For the most basic simple conversion, the GNDs and connected together as are the D+ and D- pins. The power has to be connected to VBUS lines and CC lines which allows USB-C to work in any orientation.
The problem is that some cables do not connect the power to the CC signals through pull up resistors. This is used for high power delivery and is used to negotiate power delivery. By default, these should be pulled high, then the phone will pull them low to request higher power modes.
The host acknowledges and approves the request by pulling the lines low in response.
Certain cars will disable the interface if the USB device tries to pull too much current, others will supply higher levels ok, without disabling the interface.
So long story short a USB-A to USB-C cable can be designed to following:
- Power Delivery only - Only VBUS and GND are connected.
- Low Power USB-C Device - CC, D+/-, GND, and VBUS lines connected, but no pull up resistors for CC.
- Full Support - VBUS, CC pull up resistors, D+/-, and GND lines are all connected.
My converters work fine with any USB-C device that does not need or request higher power modes but failed with the iPhone 15. In this case because CC is pulled low by the phone the USB host in the card was detecting a short and shutting down the interface.
Image sources:
This introductory article will look at some of the most important features of the USB-C standard.
www.allaboutcircuits.com