I've had 2 dishwashers apart in my short time on this earth.

They both only had one pump, and a solenoid valve that ported the pump's discharge to either the tub/sprayers or the drain line.

I remember replacing a pump assy for $150 a year or two ago - still cheaper than a new dishwasher, but not as cheap as a craigslist dishwasher IIRC

High-end dishwashers might be more complex though.

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2009 Kia Sedona
2009 Honda Odyssey EX-L
12006 Jetta Pumpe Duse
(insert Mercedes here)

Husband, Father, sometimes friend =)