Sounds like you have what I call a "high resistance open"!
The wire is not fully open so you get enough current through to let a meter read it. But when the motor tries to use it and needs far more than the meter, there is not enough contact to let enough current flow for the motor to run!
OR, an easy one to walk past is a bad ground as that power that the meter reads may be enough to work but it can't if the other wire going bad to ground doesn't let it have a full circle, (open circuit?) So when we get to a connection, it can save us time if we check the power, look for clean conntact and also look for that return to ground. That's where having the exact right drawing can be a big help becasue it should tell us what color wire and we can check that with the wire ID and also we should know which direction to klook on that wire and expect to see battery. If we see battery looking "left" we can then look "right" and have to see ground!
One way to cut the chase in half, if we know the full circuit is to go to a point somewhat in the middle and check a connector, looking toward the battery and toward the ground.
On a bad circuit,one will be missing or funky, so we know to move in that direction.
I never know the folks on the other end of posts, so don't let this offend if I'm telling you lots of things you already know. Lots of folks reading along may not know and I like to make it clear what I'm getting at when they may read it two years from now!
And it is always true that what I do is not the only way, just the way I currently see doing the job!
Lots of different ways to paint a house!
This is something that can happen in lots of ways but one of the more common would seem to be where the pins of connectors get slightly corroded and only make a half hearted connection, rather than a clean solid one.
How to find and fix can be shotgun and maybe quick or slower and testing each connection along the path. Sometimes a combo of each works good as how and where the connections are located and what it takes to get to them makes a big difference! Of course, it could also be as simple as one of the switches being corrroded, worn, etc. Those switches are almost always easy to find but getting them out of the wall can be a trick, at times.
See up there on post 5 where it shows that connection as "under shower"? Next big question comes down to what does it take to get "under the shower" to that connection!
So before you start doing the duty to take things apart to get under the shower, I like to first get down solid which parts you will actually have on YOUR specific RV as each RV may have different options and number of switches.
Mid level, low level, or no exterior shower at all, is what I'm seeing in the notes, so finding which you actually have on YOUR RV can cut the chase really quickly if you don't have that part.
Knowing which parts to expect to find, like how many switches you have can let you skip over looking for parts you don't have!
My work has been in repair on really complex wiring things where you may start with 15-20 sheets and spread them out on the floor to start tracing! That made me learn to first sort out what I could ignore as not part of the problem!
Good to check and clean each connection but not if it means taking a wall apart??
I think the drawings will give a pretty good shot at locating each connection but then knowing if that space is something you can get to easy enough to make it practical takes hand on looking.
As a second way to get some info on where they may have put things, have you found the "installation" drawings on that same list?
They give us the schematic for wire by wire info but then the install set can give us a better idea of the physical location of things. I hate them as they usually get so messing and hard to read which way the tiny little line goes but if you can see the wire AND the drawing it makes more sense of things!
https://www.winnebago.com/Files/File...992/105169.pdf
Down on sheeet 7? But where is the shower? That has to be the hands on looking part!
Click this snip to get better view!
The thing about this pump circuit that makes it tricky is that it is not just an on/off deal with simple switches that open or close. But when one switch is open to turn the pump off, we also want to be able to turn it on from a different switch, so we have to have double throw switches!
That means when you check a switch is letting power through in one position, you also have to check it will let power through on the second path when left thrown in the other position!
A far quicker way to sort this might be worth the time as "shotgun" work may find the problem.
This requires ALL the switches to work ALL the time. So if you have three switches, you "might" find the whole thing is bad only when one switch is set to some specific position! Since it could be a bad switch or a bad wire connection, one might try setting switch one to left or right, then go to the other two switches and find if they work. If not go back to that first switch and repeat the test again. Kind of looking for luck but if one goes through flipping each switch and then trying the others, you might find one combo that works while other combos fail??
I'll let you decide what is whorth the time because either way either testing slowly or shotgun may turn out quicker! It's hot and I hate to think about getting under the shower, etc, if I might get lucky by flipping the swiches to find I can cut the chase a bunch!
You've got a tricky one, though!
Like lights in a house that have several switches, I hate them as I don't do it often enough so that I have to set and think really hard when I do get into one!
I now have a working water pump and all three switches work!
Linear Mode
