Sink drainwater leaking back into dishwasher

Dishwasher Repair
1

After running hot water into the sink for 5 mins water began filling into bottom of the diswasher. We thought the sink and garbage disposer were partially clogged but it drains well. Is there a check valve to prevent drain water from entering the dishwasher?

Thanks

Bob

2

Although not for your model here is a good dishwasher install sheet.
Check that your drain hose is installed correctly.

Please see the following install sheet
http://products.geappliances.com/MarketingObjectRetrieval/Dispatcher?RequestType=PDF&Name=31-30515.pdf