low points drain

Color, material (pex or not) and size will tell a lot about what you are really seeing on your trailer.

On our last TT the va!ves for the low point were behind a removable panel under the shower. The TH before that they were under a drawer. Look above the drain inside the trailer.

Also look inside cabinets for small T handles the you need to pull up on to open the low point drains. Many trailer use these instead of valves or caps on the ends of the tubes. Often those T handled valves are in a plastic pan that is located below the level of the cabinet floor - sort of like a plastic pot hole in the floor. :)
Barney

NORMALLY,

You would have 2 low point drains.. 1 Red and 1 Blue, BOTH should have turn valves OR end caps..
Then you should have a fresh water drain, possibly white also with a turn valve or end cap..
And lastly you should have a fresh water overflow line, this should be the only line with no shutoff and no end cap ..

If you have underbelly wrap, try to look up and see if the shutoff valves are above that??

I don't know that trailer model, so this is just guessing, but there may be more than one low point created by the plumbing lines changing elevation along the length of the lines. In fact, most trailers probably don't fully drain from a single low point location.

As for no valves, mine doesn't have valves either. Just blank end compression fittings, which are the equivalent of a pipe camp. Easy to install valves if you want, for future convenience, but they chose to save a few pennies and not include them. Fine by me, since we don't winterize here in del norte.