Pontiac Problems? Ask a Mechanic for Answers ASAP
My name is ***** ***** I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
The issues here may be caused by a loss of voltage or ground to the vehicle electronics causing this fault here.I have seen poor power connections at the fuse panel under hood as well as in some cases corroded power or ground connections to the battery itself.The other issue that is fairly common on this model as well as others is the electronic ignition switch acting up needing replaced.
For the no start issue with the new or used PCM installed this sounds like the vehicles theft system has engaged.This will need to have the theft relearn done to correct this here.I may be able to post this relearn but first I need to know which year you have as you have posted this is a 1999 as well as a 1990.