When trying to work through a problem like this you need to go the wiring diagrams and determine what loads are on the breaker that was tripping. For your rig, the drawings are located at
Table of Contents. To address future issues either by yourself or a RV mechanic, I reccommend you download the full drawing at the bottom (contains all as well as additional info) as well as any portions you may want.
In this case:
1st step: You have to determine which circuit the breaker is feeding. That is found on upper right page 3 of the Chassis Wiring Diagram (
http://www.winnebagoind.com/diagram/...ire_145017.pdf). The breaker that is tripping is circuit "J".
2nd Step: Locate wiring diagram that includes the breakers. In this case that is the 12Volt Body wiring diagram (
http://www.winnebagoind.com/diagram/...ire_145020.pdf). You will find the breakers on pdf page 7 and it shows that the circuit "J" breaker feeds the lower set of breakers on the 12 volt distribution panel.
3rd Step: Determine what breakers are on that panel. You can go look at the panel or find it in the drawings. For this example, it is on pdf page 5 of the 12 Volt Body installation diagram (
http://www.winnebagoind.com/diagram/...ire_145018.pdf).
Step 4: Now you can determine if you overloaded the breaker by having to much on at once. In this case I would ask did you operate the sofa while several other things where on and it overloaded the circuit? Please note that the total amperage for the breakers on the bottom half of the panel total 112 amps. That is greater than the 55 amp breaker. These setups are designed around the concept that they do not expect all feeds to be ON at once. It is a balance of what they expect to be ON at any given point in time.
You have to be sort of a detective with this type of stuff. It does require just siftting through the documentation hunting for the specific piece of information you need. Havng the documentation is the first step. You are lucky in that Winnebago is aboutthe only RV mfg that provides this information freely to the public.
Dave