You can't work on newer vehicles without the right tools. You pretty much have to have them or pay someone for the repair. And you will spend a lot of money trying to replace parts based upon someone else's fix with the "same" symptoms.Thought crossed my mind when I purchased the OBD reader. Start collecting the right tools.
Did the new pcm happen to fix your issue? I'm running into the same bypass solenoid code and everything seems to be working up to the pcm on my end as well...I've got voltage running through the senor connection and I tested the old, and new, boost solenoid sensor with the "9volt battery" trick. Both sensors are working. Check engine light went out but I'm still limited to 1-3lbs of boost.
How to check your GM boost solenoid
I have a ZZP 1.0 LSJ PCM on order.