The Joying brand of android headunit may have a small black connector labelled KEY.
The Joying android head unit models can be considered universal fit. But they do have their own system for connecting the KEY wires that can cause confusion. The Joying KEY is a multi purpose connector. The KEY configuration will influence the operation of the factory fitted steering wheel controls (SWC).
How to connect the Joying KEY connector
If you are installing a universal fit Joying android headunit, that does not have a CAN BUS BOX. That does have a small black 2 pin plug with white wires marked KEY. And another small black 2 pin socket with green wires marked CAN OUT. Then connect KEY to CAN OUT and the other loom with have SWC connectors suitable for your vehicle.
Volkswagen, Honda or Toyota
If you are installing the Joying with a manufacturer specific CAN BUS BOX option for Honda, Toyota or Volkswagen. Connect the small black socket with grey wires marked CAN IN, to the small black plug with the green wires marked CAN OUT.
CAN IN->CAN OUT
The SWC connections will be made over the CAN BUS.
BMW E39, BMW E46, Ford Focus, Jeep
When you are installing the Joying with a manufacturer specific CAN BUS BOX option for Jeep, BMW E39, BMW E46 or Ford Focus. Connect the small black two pin socket with purple wires, marked IR to the small black plug with the green wires marked CAN OUT.
The SWC connections will be made over the CAN BUS for BMW E39, BMW E46, Ford Focus and Jeep.