Po717 on new transmission

Marshall Lb7

New member
Apr 10, 2022
Swapped my trans filled it up with fluid pretty sure it's topped off. Took it down the road a couple houses. It shifted to 2nd gear u back out of neighbors drive and it took like 1500 rpm to take off maybe a little less.... so I parked it read codes and I got the regular trans illum code and the po717. Where shoukd I begin?