Hey guys,I have a 2012 l96/6l90e and I'm in the middle ofmaking my engine and trans harness stand alone . But I'm stuck on a few wires. Since I'm not using the BCM , I want to put in a OBD port . I have the can bus wires from the ECM and TCM to a plug that passed thru the fire wall and they are not connected. The TCM is located in the transmission , my understanding is I need to go " ECM to TCM to diagnostic port" well I can connect them from ECM to TCM but how do I add the OBD II port ? Thanks guys