I can believe it. I have Googled this and found many other people having similar issues, but so far nothing has worked for me.
The drain hose is connected to the sink drain pipe (no garbage disposer), about 4 inches below the sink drain itself
Up, then down, actually
Yes, about a foot above the drain into the sink. There is no air vent to the countertop, just the hose.
Unless the dishwasher pump has a check valve built-in, then no
how big of a bucket will I need? I have a couple 5 gallon ones, I assume that'll be big enough
of course :-)
if this does turn out to be the issue, what could I do to fix it? I've read that an air gap to the countertop is the only sure way to prevent siphoning
alright, will do. Thanks for your help so far.
I tried your suggestion of draining into a bucket, and learned something important--most of the drain cycles (and even some of the wash cycles) were completely skipped. I have the service data sheet that details exactly when the drain is supposed to turn on. In the cycle I ran (eco wash), it's supposed to wash/rinse and drain 5 times, with one additional drain in the middle of the drying period, for a total of 6 drains. Instead, the drain pump only turned on twice: once after the very first wash cycle, and once in the middle of drying at the end. The four times in the middle when it should have drained, it did nothing--the bucket was empty.
I also noticed that during 3 of the 5 wash/rinse cycles, it did not fill with water, or do any spraying. The heating element turned on at the correct times, but aside from that it basically sat there for 45 minutes doing nothing at all.
Some good news: The tub did not have any water left in it at the end. So you may be right about the siphoning issue. But it sounds like I have bigger problems--I'm guessing the control circuit or timer is the reason it's not washing and draining at the correct times. What do you think?
Yes, I am pretty sure I'm reading the data sheet correctly. I suspect the sheet is incorrect about some things, since the timings don't add up to the actual length of the cycles, but it does generally agree with the user's manual which you can find here:
which indicates that Eco Wash may do 3 washes and 2 rinses.
Regardless of that, I tried a Normal Wash cycle today and monitored what it was doing. The first two cycles (wash/rinse) went normally--for each, I could hear it filling up, pumping/spraying, then draining at the end. However, the third cycle had a problem. Here's the sequence of events for that cycle:
According to the tech sheet, it ought to be filling, washing, and/or draining during all of this time. A brief pause I can understand, but 20 or 30 minutes seems crazy. After waiting for 51 minutes with nothing happening, I opened and closed the door--it immediately started washing again, and blinking "HO". Then after 5 minutes it stopped again. After a few minutes of nothing happening, I opened/closed the door again--once again it resumed washing. A third time it paused, and a third time I opened/closed the door to make it resume. Finally, it drained and entered the drying cycle.
This is consistent with what happened during the Eco Wash, and it's also consistent with the lack of drainage, and dishes coming out dirty--it's like it gets stuck in mid-cycle, and won't resume unless I open/close the door.
I've looked inside the front panel, and there does not appear to be a mechanical timer, only a circuit board. I can see no visible damage or loose connections to the circuit board. Considering how opening/closing the door seems to make it restart, I wonder if it could be a bad sensor in the door latch mechanism. It looks like a new control board is about $140, so I'd like to rule out the possibility of a sensor malfunction before springing for that.
Do you think there could be a problem with the door latch or some other sensor? I'm electrically competent enough to test them with my multimeter, if necessary. Please let me know if my hunch makes sense. And thanks again for your patience in helping me figure this out.
I tried as you suggested--the heating element itself is good (resistance of 15 ohms), so I took out the thermostat and tested it. At room temperature, it was closed (had continuity). After heating it up to 180F with a hair dryer, it was still closed, so clearly there's something wrong with it. I tried simply leaving it out of the dishwasher so the connection would be open. Two full washing cycles ran perfectly! I've ordered another thermostat, and I'm pretty confident that will fix the problem for good.
I would not have thought that a faulty thermostat could cause drainage to fail, but there it is. You nailed it! Thanks once again for your detailed suggestions and explanation. Finally, I can consider this question answered.