Hi and welcome to FixYa, I am Kelly
This is usually caused by the plastic float in the bottom of the unit being stuck OR a failed float micro-switch.
The parts you need to look at are items 302, 305, 306, 307, 308 and 490 this link:
http://www.appliancepartspros.com/partsearch/model.aspx?model_id=5224401&diagram_id=26124425#d26124425
Check the stem from the BOTTOM. It should slide up and down freely. Listen for the microswitch to CLICK as you lift it up and down. No click = bad switch. If it is sticky you will have to remove the float and clean the whole assembly.
Concentrate your efforts in this area and I am sure you will resolve the issue.
Thanks for choosing FixYa,
Kelly