Dishwasher fills and heats water, but doesn't wash.

To tell you the truth, I don't even know what model my Whirlpool is. However, I had this same issue. My dishwasher would fill, but it wouldn't spray the water. I could hear it hum, but the motor wasn't going.

After no success finding any ideas online, I had to call out the repairman. Well, 5 minutes and $109 later it was just a simple matter of the motor being stuck. Apparently this is a common issue with GE, but not as common with Whirlpool. Just a seal that gets stuck if you don't use it for awhile (even though there hadn't been any long stretch for me). He reached in/under and turned the motor a bit over a half rotation before it broke loose. It fired up... I wrote the check ... and he left.

He advised me to run the washer on the rinse cycle at least once a week.

Hope that helps someone.

I removed the bottom cover, make sure that the dishwater was off, turned to motor blade with a screwdriver clockwise (I saw an arrow and figured that that was the direction to turn the blade). After a small tug, the motor then moved freely). Powered the dishwasher and it worked like a charm.

I disassembled the bottom spray arm assembly to find a piece of chicken bone wedged against the motor gear. There was also lots of food debris lodged in every crevasse One main hole in the spay arm had paper lodged in it. So it was beneficial to do the extensive cleaning.
The dishwasher fired right up after I put all pieces back together.