Does the scanner tell you if the codes are active or in shadow memory? These vehicles will store historical codes so even though you can read them, they may have occurred long ago. I'll have to look at the wiring diagram to see if it might be something obvious. I got the parking gear sensor message before but it's because I messed up reinstalling the valve body & didn't have the sensor engaged. You would get the same message if you tried to engage the mechanical neutral override. In fact, I would cycle the neutral override and see if that helps. You can do that by getting the red handle from the emergency tools in the trunk (whatever the back area is called), removing the rubber from the bottom of your cup holders, and removing the false bottom on the cup holder nearest the driver. Set the parking brake, insert the red handle into the socket below, turn it, and release. The transmission should go into neutral and then go back into park.