Cannot shift car out of park

Well on top of a never-ending charging problem(cause unlocated) is the fact that now the vehicle a 1999 Ford Taurus 3.0 automatic cannot be shifted out of park. Could this be a "side-effect" of the charging problem?
I have repLACED THE BATTERY THE ALTERNATOR, CLEANED THE NEGATIVE GROUNDS(ALL), REPLACED THE NEGATIVE CABLE ON BATTERY. ALTERNATOR TESTED OUT FINE BATTERY TESTED FINE BUT still I have a dead battery if I dont tAke the neg cable off at night or if I use lights or airconditioner etc. And do not recharge the battery. I'm trying to locate a schematic to the fuse boxes both under dash and hood to use ammeter but cannot find. If you could throw any suggestions my way I would greatly appreciate it.