Aux Tank & Valve "Weirdness" on Concord 300TS

[RustyinBend]

I have a "question" ... and a "weirdness" on my 2018 Concord-TS after my first camping trip.

The "question" is ... what the heck is the gray tank valve for? I'm assuming it equates to the "Aux" meter on the control panel, but I just finished a 4-day dray camping trip, using every drain on the coach, but the Aux gauge always reads "E", and the Aux Dump Valve open or closed, does nothing.

... and now something that might be related ...

The "weirdness" is that the shower (and only the shower) drains directly into the main dump pipe even when all dump valves are closed (Black, Gray and Aux).

If the "question" and "weirdness" are related, I could infer that (a) the Aux tank is for the Shower, and (b) the valve is broken because when closed, shower water still drains into the main exit pipe.

Oh exalted Concord Gurus ... am I aimed in the right direction?

[wahoonc]

There is another valve on the right-hand side near the wheel that closes off the right-side gray tank.

I can't remember if the left tank is Aux or the right side.

On the TS the left side tank is the kitchen sink and bathroom hand sink. The right-side tank is shower only.

Aaron