I installed a Joying unit, connecting and programming SWC is very easy. Our buttons send a unique resistance value that I could program for all the OE functions.
In addition, I pressed the |<< and + simultaneously to give me a mute function as well. Its not difficult to trigger with 1 finger and any combo you have the dexterity to press you can create.
Thanks for posting this, I’ve been trying to find these wiring diagrammed for ages. I thought the steering control was the IE bus on the 18 pin, great to know it’s Resistance controlled and on the main harness.
One question on the main harness, my car (2013 basic spec) has no ground wire in its head unit harness (no wire in pin 11 at all) instead relying on the antenna ground, is this the same on yours as I see you’re using that ground?
I have a dedicated ground in the harness. I can't give you a color since all wires in my harness are gray except switched 12V (red) and speed sense (purple) in my '21 G4.
I would chassis ground to a dash support near the stereo instead of relying on the antenna.