Are you running piggy-back?
I am not sure what do u mean by OBD to work.
But in general, a M400 uses CAN network and the UTC Adapter is needed to connect to a computer or laptop.
http://motec.com.au/commscables/commcan/You will need the M400/M600/M800 to CAN connector wiring #61037, (If you don't have it with your M400)
and the UTC, USB to CAN adapter (includes USB cable) #61059.