This is such a informative post, I had to register and show OP my appreciation.
One question tho, Lets say I'm using #3 on IEEE-1394 connector for analog 1. Do I need to ground #4 which is analog 1 grnd? Or I don't have to since its being grounded at OBD port by SCT?
Here is the link that says I should ground the analog 1 grnd.
I just wanted to make sure which is the right way.