how do I connect to the factory CAN bus?
 

any have idea where is the factory CAN bus so I can connect my ecu to it?

there are CAN wires at the OBD port. If you look at an OBD wiring diagram it has the pin outs :)

Talking to it in a way it understands is a different kettle of fish ;)

There's always the CAN-BUS Shield adapter for Arduino systems.

thanks!

for future reference, here's the pinout of the OBD harness.