Ivan K

The level should fluctuate quite significantly between cold and hot, eventhough I know that it takes for ever to cool down in AZ. But, if you are only concerned with the sensor...
Here is a McGiver way at own risk but it wouldn't be the first time it was done.
3 wire means there is a reference voltage on one of the wires, one ground and one return signal to ECM. I would disconnect and confirm the voltage and ground wire first. A dirty way of faking the signal is disconnecting the connector and shorting the reference (~5V) wire to the return wire. These could have the same color. NOT to the ground, which might be a white wire!

Have you tried to reset the thermostat and swap and reset them if it made no difference?

Check the color of your fluid. Mine is red ATF Dexron. The new Dexrons are back compatible with the older lower versio number, just check the label if you have the same.

The short cylinder is to equalize pressures and synchronize that longer rams. If you have the option to remain stationary and have the cylinder locally rebuild, I would do that. I had mine rebuilt for just around $100, same day turnaround. That would remove all the workarounds. I have traveled with a leaky cylinder and it can be done but do you really have to?

Rick, I pulley spare controller and meassured between C1 and C5, like in the picture. 9 Mega Ohm one way and totally open the other, appears there would be a diode or transistor in that circuit. Wish someone came up with a diagram for that board.
 
BTW,  are you saying that the high temp thermostats are one time use only?

I have used the one below with success. It cures in short time and is green. I got it at Napa but should be pretty common. 

I also tend to agree, not an error, his computer tells him that there is a newer update available.  I would also not mess with it without knowing what's in the update. Suspect nothing beneficial, not for you anyway.

Good deal. If yours are 22.5" in decent shape, should be sold on Craigslist or Marketplace in no time. I was getting inquiries all night after posting them and gone in the morning to the first guy, for his rock trailer.

Here is a pic of my walls cross-section, right hand side is the outside. Looks like ~1/4" of solid surface.

Normal with this one piece roof, usualy fiberglass, sometimes aluminum. It is only attached at walls and caps and otherwise floating. It would feel solid around the supports for major openings, like for the AC units, elsewhere it will flex a little.

I had a pinhole at the bottom outside of exhaust port, not in the burner tube. Before tearing it apart, I tried boiler fluid sealant and it stopped the leak, probably 6 years going now. That may or may not be worth a try since yours appears to be in the high heat area and sounds more than just a drip. Could be a last resort before taking it out.

Remove just the brass plug with a hex tool.

Best I can do when I stick the phone past the cablemaster drum from driver side pointing to the rear over and past the AH between frame rails. That's on 2000 Sig.

To close this topic, I hooked the residential Starlink (same HW as for RV account) to an extension cord from our Trace MSW inverter for couple of hours and it worked just fine. A tiny bit of AC buzzing sound at few inches distance from the little transformer inside power supply portion of the router but there appears to be enough filtering of the harmonics, judging by the coils and capacitors, in a picture of its guts that I have seen, to not concern me much. Absolutely no temperature increase either with an IR gun. Looking forward to staying longer in some places where my wife could feel as being too much off grid after few days of potentially having no one else but me to talk to 🙂

Not sure if it's the same but given the year, it could be. My electric element is getting power through a contactor relay in back of bedroom, inside shore AC breaker box cover. Not the inverter box.There are 2 of them in my box, for block heat and AH and they click when the 12v switch is turned ON, easy to identify if they still work. I had to replace some of the spade connectors. Not sure why the image uploaded mirrored but you get the idea.

For instance, here https://www.camperid.com/jr-products/jr-products-14v-10a-switch-indicator-light-1077394278.html
Or https://www.amazon.com/JR-Products-13315-Indicator-Switch/dp/B0031XOYCS?th=1
I just replaced the burned bulb with led.

To remove the rocker switches,  you have to get behind them, squeeze their top and bottom tabs and push them forward, out of the panel.