The 4L80E I have started acting like the converter was going bad the other day. Like it was slipping. But upon further diagnoses it is not the converter. When you put the truck in first the truck goes great shifts through all the gears. When you put the truck in second, it will start out in 2nd like it is suppost to. (Aftermarket tranny controller)

However when I put the truck in OD the truck will sometimes start out in 2nd and sometimes start out in first. And if you give it half throttle or more the tranny doesnt know what to do and starts shifting back and forth violently causing the whole truck to shake.


i have replaced both shift solenoids and it is still doing the same.


Also I know there is an actuater screen in the valve body. Could this be clogged, causing incorrect line pressure to the solenoids?

Anyone have an ideas?

Problematic shifting can be caused by a multitude of things. A can of worms. Your job is to pull those worms out one at a time.
Check the connection at the transmisison and see if it is free and clear of oil. All pins are good and not pushed in male end and the female end.
Throttle position sensor. If you have one of those electronic injectors its not my forte'.
The Transmission range pressure switch can cause shifting problems especially since you tell me you are placing it into second gear.
Check out the sticky.
My advice? Check all grounds. Check the TRPS switch as noted in the second paragraph.
Retrieve codes.