Well, i'm back after a month long hiatus.
It's not the SI batteries. I swapped out several clusters from 318's, 325's and the M. I used the correct coding plug each time. No dice.
So, I don't know if you guys have seen section 6210 in the ETM for our cars, but the diagram seems to be lacking the attached wires from the blue, yellow and white harness. If I am reading it right, all that is show are the light bulbs for the blinkers, idiot lights, SI the main board and all associated.
So I am trying to figure out which wires in the blue and white harness are what. The yellow harness is useless and unnecessary for my setup. It is disconnected and has been for months.