what have you gotten done on your blazer today?
#7004
No need to yank valve body for that. That code is usually just from one of the shift solenoids - not a given (nothing is with these electronic wonders), but usually. Very easy to swap those out, and even from GM they're under $30. If the truck starts out in 3rd gear and only shifts to overdrive, then it's the 1-2 shift solenoid. If it starts off ok but won't hit 3rd or overdrive, then it's the 3-4.