Only the manual TC shows the ECM getting the 4 Lo signal direct. I tried to wire my ECM this way with no luck; my VSS reads the same with signal or not.
You are correct Robbie, only the manual TC has that 4wdlow connection to the ECM. That is what I have to use, 'cause my old '97 TC and the TCCM has no other connections to the ECM.
Just to be sure I'll email you some schematics to compare with the Mitchel manual. ( I also have the Mitchel, an Alldata subscription for the '07 Suburban, and the GM manuals from '07..)
Harald