The "junction box" is what you are thinking of behind the tub on the front frame. There are a number of threads that discuss the setup.https://tab-rv.vanillacommunity.com/discussion/15356/j… (View Post)
What year is your trailer? The newer trailers have cassette toilets, and different Hepvo sink traps. The pump is very simple to drain and clear water from. Lots of threads on this, so: what year is y… (View Post)
There should be a "spout" that sticks out from under the coroplast cover that allows the water to drain out under the trailer. Crawl under the trailer and see if you can find an un-occupied… (View Post)