Product review (5 stars): I suspect either the water valve itself is bad (though I still get water to the water dispenser)
The ice maker in my 15 year old Whirlpool refrigerator stopped working recently, and being new to this kind of repair, I did a lot of online research.  My fridge has both an ice dispenser in the door, as well as a water dispenser.  The water comes out full force, so I figured it must be something in the ice maker itself.  I ordered this unit before doing additional research.  It came very quickly, and by the time it came, I had found out that there were test holes in the "head" unit that your could insert an insulated probe, and manually start the harvest cycle, as well as manually open the water valve to fill the tray.  This replacement unit was identical in shape and size, and exchanging it out was a quick 15 minute job.  Unfortunately, while the harvest cycle worked, the unit would not fill with water.  Inserting my test probe into the "V" and "L" holes triggered the water valve to open, and the unit filled up and completed its cycle.  Then my test probe started getting intermittent results with the tray filling, and after a day or so, I couldn't get it to fill at all.  I suspect either the water valve itself is bad (though I still get water to the water dispenser), or possibly something in the internal wiring, which wouldn't be an easy fix.  But my reason for giving 5 stars is do to the excellent service by the vendor.  I sent an email after having the new unit installed for 24 hours, and they immediately sent me a replacement unit, along with a pre-paid shipping label to return the first unit.  I don't believe there is anything defective in the unit itself....it's just a problem I haven't figured out yet.  But there level of commitment to good customer service has earned them 5 stars.