Thread from 2016:
Long story short. Installed new garbage disposal. Dishwasher stopped draining. Checked for clogs, cleaned drains, etc. Replaced pump and motor assembly (including drain valves, etc.) when they were found to be leaking anyway. Impeller blade also broken off upon comparison with new parts. Run again and it still wouldn't drain. Found plug in the new garbage disposal for the dishwasher drain inlet. F()*#&$)&qy$p. OK, remove plug. Run washer again. Still won't drain. I'm stumped. Of course we're having family over tonight and will have a ton of dishes to do later. HELP! Thank you!
Before you reconnected the drain hose to the new garbage disposal, did you knockout the plug in the center of the barbed connection on the disposal? Not everybody has a dishwasher, so those barbed attachment points come with a plug in them or else the water from the sink will just pour out of the barbed connection. Its cast in there and is pretty solid. Remove the disposal or get your head up in there with a flashlight. Remove the DW hose and look inside there. That black solid piece needs to come out. Easiest way is to whack it with a big flat blade screwdriver or a 1/2" socket extension. Whack it hard because you need to break it off. It will end up inside the disposal and you will need to fish it out before you turn on the disposal. It will look like a black pocket chip.
I found that plug on first inspection. Of course there is no mention of it in the garbage disposal installation instructions. 
Just ran again and now it is draining. Phew. I've got a slight drip from the connection between rubber drain collector and the bottom of the washer tub now. I've rechecked the seal and it is seated right. Right now though I have other things to attend to so I will keep an eye on it and fix sometime this week.
Check for food at the inlet of the discharge pump
Also it helps if you run the dishwater hose above where the disposal attachment is in some kind of loop. This will help prevent disposal crap from running into the dishwasher hose which WILL plug it eventually.
Was just going to post what Rufledt posted. Wouldn't hurt to put I believe is called an accumulator in the drain hose above the garbage disposal but as long as it is above the disposal should work. The make a special T connection for this. Isn't expensive.
In reply to richardenciso :
Thanks, Canoe.
Wait a minute. My dishwasher won't drain now. What a coinkeedink.
In reply to spitfirebill :
You got sabotaged by a canoe. It happens sometimes.
