It wont shift but into n.1.2 r no3rd drive and overdrive
Is the Check Engine light on?
Tester
Yes the check light is on
Then you need take the vehicle somewhere and have the codes retrieved from the computer. Some auto parts stores will do this for free. So call around and ask.
Until the code numbers are known nobody can say what’s going on.
Tester
Thank you
Check fluid level. No OD is usually 1 issue but no 3rd gear could be another. But usually no OD on any auto trans is not good. But, those GM trans are easy to find used in junkyards. A rebuild is 1600 and a used install could be 1/2 that if u shop around. Your car is not worth a lot.