4l60 shift problem

[Jeffhaynes]

have a 01 silverado 5.3 with 4l60e. never had problem and let sit for week or so now it won't shift out of 1st until let off gas then shifts thru all the others like normal. I've tested shift solenoids with 9v battery and shift valves wasnt gunked up. anything else to check before put pan back on. I changed filter but didn't want to put it back together without checking.

[davester]

are there any tcm codes (you need a more advanced code reader to get them, if they are present)?