starter start with dei 528t

Cut the wire that goes from the tranny to the IPDM.  You need to make sure that that signal is working properly.  The service manual states it is a + wire, but I've seen mistakes in the FSM before.

I say to cut the wire because you will want to leave all the other wires hooked up while you are doing this test.  You need to cut the wire to isolate the signals from the IPDM and the TCU.  In a perfect world, with the wire cut, when you try to start the car there will be (+) voltage on one side of the cut wire and ground on the other side (thus energizing the internal relay).