This looks like the kinda setup: https://www.cowfishstudios.com/blog/obd-pi-raspberry-pi-displaying-car-diagnostics-obd-ii-data-on-an-aftermarket-head-unit htt

This looks like the kinda setup: https://www.cowfishstudios.com/blog/obd-pi-raspberry-pi-displaying-car-diagnostics-obd-ii-data-on-an-aftermarket-head-unit https://www.cowfishstudios.com/blog/obd-pi-raspberry-pi-disp... Also a search for "reading OBD diagnostics with raspberry pi" brings back some promising results.