I've ordered a EndoscopeInspection Camera with Articulation Head coming to look inside there and try and see where that wire goes or branches off to.   I may never know, but if I pull the panel then I can cut the wire at branches and see what happens... then I can always add a switch to control it in the future.

Yes, it will be interesting when I find it.

I also just discovered... the Bath fan is NOT on that circuit (the light is).. so the factory label is incorrect.  So I need to trace those wires.  Unless someone has a better idea.   I have figured out a way to cut that panel out and the one above it and make it a door I can remove with 4 screws for each panel.   

I've had the RV power supply out... so I know the wiring in there... and need to start there again and see where # 4 goes.

Any more ideas?

One of these days I hope to post photos of all the Mods.

I would check that anyway. You can take the plate off and check the wires behind it to see if perhaps there is something going on there. It is better than to start cutting holes in the walls.

Back to the drawing Board.

Those are stock speakers as far as I know and right now. I disconnected the power to the radio and that eliminated about .12amps... but it does have a antenna on the roof or maybe that's the TV... I don't know.   What I do know is I'm still drawing .35amps (3.5 per day) on that circuit with nothing on that I know of.   What I know is one LED light draws about .1Amp.  My various instrument indicator Displays are in the .0? (1/100 amp) range.

So something big is drawing .35amps all the time (3.5 per day).  I've been pulling my hair out on this...  Hundreds of hours.   I wish I knew everything on that circuit... which is why my spring project mayl be to tear into that panel.   Maybe I'll turn it into a door panel.

Al  ideas welcome.

Schematics only show the logical diagram of what connects to what, not where the wires run. They are helpful to a certain extent, but don't help when you are trying to find the wiring in reality.

It looks like you have done what I would have done by pulling fuses. As for the speakers, I don't think the ones in the RPods are powered unless you also have a subwoofer. I don't think the 2019 does. The stereo unit does draw power, even if you turn the brightness of the display down. The lights should not be drawing power unless they are turned on. The same goes for the fan if it has a physical switch to turn it on and off. I'm not sure about the ones that have the rounded push buttons. The Maxxair fan in our Cherokee has the buttons for speed control with a second one to turn off. It may be drawing a little power to be able to sense the buttons, but I have not checked.

I guess you could pull all the fuses except the 40A reverse polarity ones and then plug in one at a time and see what works and what doesn't. That will help you to know if there is an unlabeled item on the circuit that is drawing power. If you do that, keep track of what fuse goes where so you don't put a 5A fuse where a 20A one is needed or vice-versa.

To answer some questions.   

-I have a master Kill switch... but that kills every thing including the Charger.  But I could Add a second one... but that's no good when I camping off grid for 10 days and need the fan & lights.

I have what looks like a factory Circuit label sheet attached to my 120/12 Volt power box, that ID's Circuit Breakers and 12VDC fuses.   Otherwise I could just pull each Circuit to see what stopped working.

-I pulled fuses out to check Circuit draw changes (I like Simple).

-In addition I unhooked components in each circuit when possible to isolate even more when I could.

-I used my Renogy Voltage RV meter to see how much voltage is being use or charging.

I fully intend now to pull the top power closet/wall panels or make inspection holes to better see what's going on inside there... and cover the holes with mirror's or note Boards or something.   Will add small external switches as needed on the speakers that draw power if I can find their power cables.

Note: Good luck trying to get meaningful Wire Diagrams on the RP178's and other RPods.  You might find some... but non that say where the wires are run.   LOL...!!! 

If you don't already have a battery cut-off switch, install one for those times when you are not using your RPod and you don't have a way to keep it plugged in. The self-discharge rate of an LiFePO4 battery is very low. However, if not disconnected by a battery cut-off switch, the little draws accumulate to run the battery down. That happened to my 200AH LiFePO4 battery when I took it to the dealer and the dealer did not turn the cut-off switch off. Fortunately, the battery's BMS cut out when the battery got low. It was interesting trying to get the battery to reactivate. Since then, I make it a habit to turn the cut-off switch myself. At home, I keep it plugged in so it isn't a problem.

How did you determine it was the #4 DC circuit causing the draw? Not knowing what is on that circuit in addition to the items you cited, it would be hard to state just what is causing the draw. Do you have a clamp-on ammeter that can read DC amperes in addition to AC amperes? It would be helpful in tracing individual items to confirm or rule out which one is causing the power draw.

Another nice thing about the Lithium's is they are 1/2 the weight.   My 200amp Life pro is lighter than my 100Amp Lear Acid was.

One major improvement I made was a 40 Amp LifePro battery Charger... it charges in 1-4 hr's or less depending on how discharged the battery is.   While we are on it... make sure you have the proper size battery cables to handle the Amps from the Battery and Charger.   You must take into account the Length of the run.  Make sure the Connections are very tight and good.   If warm or hot... Bad connection or too small a cable.   (I speak from experience).  (I also had a bad factory 4.0 cable that caused all kinds of problems till I checked it.)

Good thought on the Ref Draw... but that can't be that much.

I'm seriously considering adding a switch to kill the #4 circuit when not in use.  That way I could kill the circuit when camping off grid if things got tough.

My new system Lifepro4 Lithium 200AH will give me 199AH unlike my former brand new 100AH Lead acid that really only gives you 50AH till it hits about 50% before the voltage drops below the operating voltage.   So I now have 4 times the power I had before.  I also ran test before and after the change over.  

I've always suspected our used RP used power too quickly.

It wasn't until I installed a Lithium battery and charger, Renogy meters, etc., that I could  see what was going on.  

I'm drawing .35 amps on #4 DC circuit (Bath Lights, Stereo, Fan).    That's about 3.5 amps a day.  5 Days = 17.5 amps, 10 days = 25 amps.  Not funnily when your pushing miles cross country and staying at truck stops or your new car breaks down and your stuck in a Car dealership storage lot for 6 weeks, etc. lit we were.   We called that our test run.

IS THIS A KNOWN PROBLEM?

Things I tried:

Stereo was already disconnected.  We don't use.

Bath Light was switched out to a plain on/off LED. (No Change).

I can try unhooking the fan... but I don't see how that could be the problem.

I actually have trouble shot a bunch of other problem in the major Lithium power conversion and now have a very respectable system or so I told by my buddies... but this #4 DC Circuit current drain has me baffled.   

IS THERE SOMETHING ELSE ON THAT CIRCUIT I'M NOT AWARE OF...???

Lets say I've gotten to know my R-pod very well.