09 Silverado not shifting properly

[Jhendo4591]

My 09 Silverado transmission is not shifting like it should all the time. I can drive it days without any issues then out of the blue I'll take off from a stop and it shifts extremely hard into 2nd. Other times it feels like it's slowly sliding into 2nd gear and takes longer then it should to shift. If I turn the truck off and wait about 15 seconds and start it back up it will shift without any issues and might stay that way for several days. I had autozone check it out because it kept triggering the check engine light and they said it was the transmission friction element A. So I took it to a actually mechanic and he didnt even get that code. His scanner got 2 codes reading transmission input sensor. Has anyone experienced the same problems or does anyone have some advice for me? It would be very much appreciated. Thanks

[sefiroxx]

Hmmm, your symptom of 2nd gear shift problem sounds like the typical 1-2' plastic accumulator problem.

But I would address the input speed sensor problem first. The e cu controls timing of gear shift based on engine speed, road speed, desired speed (tps). Try replacing the speed sensor , puts lined on the outside.