two things can usally cause this. the pump motor inside the door may be faulty, which locks,unlocks door.
The other is the wiring to the motor may be damaged. if you look where door hinge is you will see the cable going into the door. pull it loose and from the grommets and check if one of the wires has got cut.
The cut occurs at the hinge because theres movement there.
Ben, January 2009
