A couple days ago my trans starting acting funny. It'd want to take off in 2nd gear, unless i had the shifter in 1st, but if I shift back to drive it'll shift through the rest of the gears just fine. But thennn. Just a day ago it will only be in 1st if I put it in 1st, and there is no second now, the 2 spot on the dash still keeps the trans in 1st, and putting it in drive drops it to 3rd. no second or overdrive. No idea why, any suggestions? Hopefully someones got light to shed before I go onto my 3rd trans..but possibly its megaviper time haha also fluid levels are correct, no lights on dash, have not check if anything randomly came unplugged underneath, or if the throttle cable has lots of new slack etc

 

Unplug the 8 pin connector on the drivers side of the trans, about halfway back. Take the truck for a drive. You will have to shift manual, as there won't be any automatic function at all. If it goes into the gear you tell it to, when you tell it to, its just an electronics problem, and likely can be solved by replacing the governor pressure sensor and solenoid. If it still behaves oddly, you will have to drop the pan, and see if you find anything interesting in there.