if you get a ford key you will find any key wil lock the car but only the right one will unlock it.ln the key lock is a pin which lines up to tumblers when the cuts are right [t133423]. this gets rusty and worn and will not position so lock will not unlock.if your key turns both ways ok then its door liniing off lock out, inside the manual piece is a small light spring which breaks, its somtimes in the door bottom.when you clip motor off lock try it see if it works. l think a second hand unit complete from a breakers my be your answer if you have no wires broken. l think the fiesta is the same on in the door latch.if you look in history at this you will see how l told some one to get lock out. over the years l have done 20 or more of this problem its key ,lock spring or new latch,motor, wiring that cause the fault in that order but check wiring first
bob, May 2012
