Jenn-Air dishwasher fills for the pre-rinse cycle and never fills with water again for any other wash cycles. Yet if I put water in the dishwasher when it is on a wash cycle, it will wash the dishes and then drain it as its suppose to.
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Here is a service manual
http://www.servicematters.com/maytag_library/docs/16009308.pdf
Unlike most dishwashers where the float switch is just a safety device, it looks like the float switch on this unit actually controls the fill level.
Perhaps your float is dirty and is sticking in the up position.