Pinouts: Looking at female OBD-II (SAE J1962 spec) connector/socket, (on all Subaru diesel models so far) located between steering wheel and pedals.
Euro 4 models
____________________________________ \ 3 4 5 6 7 8 / \ 14 16 / \______________________________/
Euro 5/6 models
Pin 3 not available anymore, though, not important.
____________________________________ \ 4 5 6 7 8 / \ 14 16 / \______________________________/
|3||Proprietary||Pull to GND → test mode ON (when ignition turned ON), same effect as test mode connector.|
|4||Chassis GND||Pins 4 & 5 are connected internally.|
|6||CAN-High||of CAN high speed bus|
|7||K-Line||Serial communication, multiple control units can be reached.|
|8||Proprietary||Ignition ON via relay. Could power interface with this one instead of pin 16, see example.|
|14||CAN-Low||of CAN high speed bus|
|16||Battery+||Normally interfaces draw power from this one, so do not leave hardware connected for many days without charging the battery!|
|CAN, OBD-II, SSM2 via CAN, Extended OBD-II||6 + 14||500,000|
|KWP 2000 / ISO 14230 via Serial||7||10,400|
|SSM2 via Serial||7||4,800|
See also page Protocols listing all known Subaru relevant (petrol & diesel) protocols.