The info on the www.Appliance411.com site is great. Thanks.
Since the door had to be closed to turn on the dishwasher, I just assumed that the noise I heard when I turned it on (the motor plus a rattling sound) was the spray arm spinning.
Would the water fill valve make a rattling noise if it weren't working? Or could the noise I heard be the pump that attempts to remove any standing water? If so, how much time usually elapses before the water flow begins? Maybe I didn't wait long enough before I turned it off.