04+ Offboard harness:
You only need the blue connector and it's pin 7 for the ground.

Blue PCM connector

Blue connector 7 = ground
Blue connector 20 = 12V Unswitched
Blue connector 18 = 12V switched
Blue connector 19 = 12V switched
Blue connector 1 = CAN+ (if you want to support CAN flash)
Blue connector 2 = CAN -
Blue connector 15 = VPW Serial Data

OBD II Connector

OBD II Connector 4&5 = Ground
OBD II Connector 16 = 12V unswitched
OBD II Connector 6 = CAN +
OBD II Connector 14 = CAN -
OBD II Connector 2 = VPW Serial Data