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

DX_SIGNAL(left) and SX_SIGNAL(right) resistance value is duplicated, so a resistor is needed to avoid duplication.

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