4L80e - ECM commanding D4 shift pattern, without a DTC?

The car is a 5.3/4L80e that was running on a HPT custom OS that was a combo similar to mine. I don't know what the tune looked like, but the transmission shifted fine.

Now I swapped over to a fresh ECM to start tuning, and the transmission is ignoring the shifter position.

I started building a base tune with a 12212156 OS, did the transmission segment swap from the express van tune, and then did the COS3 upgrade. The transmission tune was modified by zeroing out all the torque reduction tables, bumping the WOT shift RPM's to 6000, and disabling abuse mode.


I know a P1810 code will cause the ECM to command the D4 shift pattern, but the only DTC I had was for the fuel tank pressure sensor, since I don't have EVAP.
I can command any gear from within EFI Live without issue.

Any ideas on where to start tracking this down? Since it was working right with the other ECM, I'm led to believe this is an issue with the new tune file, and not mechanical or electrical related.

see my reply in your other thread.