These transmissions are completely electronic and controlled by the pcm-powertrain control module, so a scan tool would greatly help you out to determine what is going on and without checking a few things you are pretty much shooting in the dark. You definately got a great deal on the car if everything else is sound! The car will feel like it is in nuetral if the shifter is in D or 3 as there is no engine braking unless you pull it manually down into 2 or 1.