hey guys i have a 2001 dodge ram 4x4 with a 318 and i rebuilt the trans at about 90000 miles due to heavy off roading.. i rebuilt it with a heavy duty conv. and planetary's do avoid any kind of breakage i also had a mild b&m shift kit added to help with high rpm shifting... now 24000 miles later i am having problems.. you see at first when i would take off the truck would barely move so i figure it was due to the cold weather and poor heating of the transmission that would not let it go. only because once on the road i would have no problem taking off again.. well a month later i now have to shift manually because just putting it in "D" will not allow the trans to shift to first automatically.. when i stop at lights i also have to shift to neutral and then back to first for the trans. to recognized the shift changing. now i'm sure this is electrical or a solenoid or something of that nature i am just not sure what it could be though. if anyone out there might know of any kind of solenoids or sensors or wires that are commonly broken or not replaced when a overhaul is done let me know or if just one is prone to break.. thansk guys!

 

there is two solenoids that are in a block bolted to the valvebody in the trans that do go bad. these will give you the problem you are having.