Citroen Xantia has resistive steering wheel remote controls.
It can be connected directly to CarPC JoyCon EX.

If you use CarPC JoyCon EX, you don’t need a resistor to avoid duplication.
Wheel1 -> DATA of CarPC JoyCon EX channel A
Wheel2 -> DATA of CarPC JoyCon EX channel B
GND -> GND of CarPC JoyCon EX