First of all, sorry for my poor English, I try to explain my idea and problem.
I'm making a carputer with my headunit JVC AVX810 and old PC.
The video and audio signals are sended OK, but the only thing that we need is to control te PC with the touch screen of avx810.
I think it's similar of your job, but the avx810 model has extraible frontal.
I've service and schematic manuals of JVC and I localized in front board panel, 4 solded points that are for x+, x-, y+ and y-.
And finally the problem and question:
I can't do the same that you make because extraible frontal can't have any cable hanging on.
The possible solution is localize inside head unit (in motherboard) the 4 signals of touchable interface, but I don't know where are placed (I think that there aren't explicit connections for these).
The touchable front panel and the headunit are connected through 2 "¿ pinout boxes?". ¿These is the only way to know how are sended the signal from frontal to main unit?¿How?.
¿Are there some way to send signal touch to pc?(I know to need usb touch controller)
¿What can I do to extract the signal from Headunit?
Thanks in advance.