why does 1996 chevy 1500 transmission not shift in second gear?

Question

I put transmission in this truck it worked fine in the vehicle it came out of and is a new crate trans. Now that it is in the 1996 chevy 1500 it will not shift into second gear drive and overdrive work. Shifts from first to 3rd passing second.

Answer 1

1996 vehicle, the PCM may not be recognizing the tire size, gear ratio or calibration .You obviously will set a code for the transmission, this in turn will set a harsh shift from 1-2. If there is any other transmission code that are set those have to b e be addressed