Did lots of internet research. Narrowed problem down to three things - door lock latch, control unit, and motor control unit. Figured out how to run the diagnostic test program, which showed a F22 (door lock) error. Removed and ohm tested the door lock (pins 1 & 3). Found door lock latch to be defective. ordered new one and installed it. YouTube video helped a lot. https://www.youtube.com/watch?v=_SjU6k5bpSs So far, so good. Have only done a few loads. New door lock latch tested fine.