Just just went through this and our black box is located above our outside TV which is located in the "peg board bay" on our 4328 behind the black plastic barrier above the TV. Had to cut the yellow wire which is next to the orange in the picture. Had nothing to do with the black tank monitor which still works. At least in our rig, there's only one black Dolmetic box and not 2 like a couple of techs reported. Looked everywhere for the black boxes including taking off wooden vents in both our 1/2 and rear baths which 2 Newmar Techs said they might be. The black box is also not located behind the rear toilet like one of the Newmar Techs said one would be.... and the black box has no Dolmetic printing on the roughly 4"x4"x2" box like one of the techs reported. Techs had me re-calibrate the monitor, unplug the yellow wire in the bay where our 50amp cord is located on the green curcuit board and completely shut down the rig from battery power. Prior to the calls we tried the salesman switch multiple times w/o results.
At least in our rig, the black tank monitor still works going against one of the Newmar Techs who reported it wouldn't.
Our issue started when we filled the black tank with 40% water and some Dawn to keep the tank clean between moves. Did it previously though and it didn't affect the red flushing light issue.
All is good now and unless there's a change, I don't see any advantage to reattaching the yellow wire.
Joe & Ro
2020 Dutch Star 4328 w FL Chassis
2018 Jeep GC Limited w Ready Brute Elite towbar