Hi,
I have not heard anything about AZ not being able to retrieve a stored code on GM vans. Do you have a S.E.S light on? Yes, your 00' has a pressure control solenoid. My van did not set any codes when the PCS went bad. If your van whines and hard shifts after warm up, I would suspect a faulty PCS. There is a technical service bulletin on this, NOT a recall though. The TSB number is 00-07-30-002B and you can ask your GM dealer to pull this up for you. It tells the tech. how to check the line pressure to make sure this is the problem. Mine had just under 80,000 mi. on the clock when this happened.
Regards,HC2000