I have a 2000 Montana with the hard shifts at times. Is a dealership about the only one that can get the transmission codes ? I have been told that the stuff Autozone has will not work. When mine shifts hard which is not often it is all shifts and even when the converter locks up. Which tells me it probably is not anything to do with individual shifts but more than likely the PCS. Assuming the 2000's have a PCS.

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:)