CaptDan nailed it.
To replace it, I found it easiest to cut a new access panel in the plywood under the bed and work from above. You can access it from he cargo bay but its at arms length and a tight fit for working on it. (Note its behind and above the water heater which is the big white thing in the picture.)
NOte (off topic) while you are looking at that picture that there is a fuse for the water pump tied into that wire bundle. Good to know if pump stops working but it means you have to take thw wall out of the cargo bay to access it.
2011 Solera 235S