Why you're trying to find connection between steering and radio?
I'm sure your radio has CAN bus (if not, then what for you need CAN bus to radio). Your steering control module definitely has CAN bus.
If you're loocking CAN bus connection place - use OBDII plug 6pin - CAN High, 14pin - CAN low.
In all renault cars all CANs goes to OBD (if they have more then one, of course, sorry if i'm wrong, with french cars i dont have very big experience). So connect there.
What exactly you're looking in CAN bus? Maybe i can help you