A flashing O/D light can mean anything, and when I say that I do mean ANYTHING, my dad's 02 Ranger had the similar problems with the hard shifting into 2nd (ATX) and the O/D light flashing and he took it in to the stealership, (covered under warrenty) they tested it the Valve Body was bad in it. So they fixed it and all is well now. So yeah the 0/D light can mean anything as well as the hard shifting.
