First scan it for codes. It only has one speed sensor which is the output shaft speed sensor that tells the PCM the output shaft speed so it can work the gov solenoid. If that sensor is bad it may not shift. We have had alot of problems with the gov solenoids and sensors. As was said if the front band was broke it would just stay in first until enough road speed (from 15 to 25 or so) then shift into third. No shifting at all either the throttle pressure lever is stuck wide open or the gov solenoid and press sensor are bad most likely. But I would scan it for codes first. Ron