Cadillac Repair: anti-theft car may not restart, climate control, battery voltage

Question
i have a 96 deville and i am having crazy problems. My PRND is flashing and i am getting a anti-theft car may not restart message. The codes i am getting are IP1552, 1P2750, AC2255, TC0077, PZ1552 and PZ2255. They appear all the time. I then bought a new PCM. The flashing went away but i cannot start the car. it cranks but does not start. The anti-theft message is there along with PZ1552, PZ2255, IP1631, and TC0077. i am stumped. Do you think there is a data bus serial 2 failure somewhere?

Answer
PZ1552 = PZM Loss of KAM. Caused by loss of battery voltage, most
                         likely by battery was disconnected at some
                         earlier time.

PZ2255 = Loss of serial data.

IP1631 = No such code. Could the code be PC1631 ?

TC0077 = PZM/PCM serial data fault.

What you need to do is CLEAR (erase) ALL the codes from the computer via the climate control panel ONLY and then recheck for codes and see if each code is a (H) HISTORY or (C) CURRENT code and let me know.

Disconnecting the battery or pulling fuses will NOT CLEAR the codes.