My wife and I recently bought a used 2012 R-177 TT, and am in the process of going through it bit by bit to learn the workings. My wife used to have a travel trailer years ago, but I am completely new to this. We're looking forward to short weekend trips, so while I am not particularly worried about the need for accurate readings on my tank levels I would like to know that they are working properly.

Does anyone have any experience with replacing these?

I crawled underneath the unit and looked at the sensors. What I found was the wires for the fresh water tank were cut. I looked at the grey and black tanks to compare them, and they seem to be intact. I thought about replacing them, but the sensors that appear to be in place do not look like any of the ones I've seen in any you tube videos on replacing them. The ones I saw looked like small rubber tubes of sorts that acted as plugs also. The ones that seem to be installed on my unit seem to be attached to a coin sized disk with two tabs on the outside of them. I'm assuming these tabs are to turn the sensor for removal/placement. The wire is attached via a screw that inserts through the center of said disk. The disk appears to be sealed with silicone or something not pliable at all. I did not want to attempt removal until I knew what/how/why I was removing it!

Anyway.....

It seems like the 4 wires from the sensors meet at a small rubber looking junction of sorts. For both the grey and black tanks there seems to be one rubber junction that all 4 wires connect to, but for the fresh tank there seems to be 2 of these junctions, and all I can see are 3 connections. 

Does anybody have any idea about this? Is there anywhere to go for any kind of definitive answer? I feel fairly confident in my ability to actually do the work. 

I'm hoping someone can help me make sense of this situation. I know there are many different permutations of campers and setups, so any help/advice would be greatly appreciated.

Thank you all in advance

Todd and Sally