Yes, if it's a Vacuflush, then it's made by Dometic/Sealand. These are very common systems so there will be no issues finding info on the net or a manual online. Before you do anything, do like mentioned above and physically verify the level in the tank. Then fill it up till it's at least halfway and see if the empty light goes out and the half light comes on. I don't recall if the empty light goes out once you get to about 1/4, or if it doesn't go out till a little more is in there. But it should certainly be out by the time you get to half.