Mice.

I used pure peppermint oil. A few drops on cotton balls in several places. No more mice!!

Update: Tried the Fresh Cab. Nope, that didn't work. Wish I could see where they are getting into the cab thru the engine compartment.

I use decon poison... we had the same problem with our farm equipment/trucks, and it was the only way to successfully control them when there seems to be an endless supply moving in and causing damage.

sprinkle a few pellets of the decon around the engine compartment and place a packet or two inside the coach... after eating the decon, they leave the coach to find water and never come back.
equally as satisfying is the fact that while they are in residence, they have something to eat other than the wiring...

after trying to plug the holes they make with steel wool or silicone, only to have the varmits chew thru another area, the decon is the most effective remedy that we have found for long term use with the very least amount of effort...

How about using an electronic trap like Rat Zapper Ultra Rodent Trap.

armond05 wrote:
How about using an electronic trap like Rat Zapper Ultra Rodent Trap.

A friend resorted to one of these when squirrels ate up his wiring in his Class C twice. I think he killed a dozen of those darn things before they decided to call his coach off-limits.

Was in a campground in the East part of the state and noticed many vehicles had their engine hoods open. Was told that if you don't want trash up on your engine or your wiring chewed you will do that.
Opened my hood the next day and sure enough there was sticks and trash on top of my battery. Left it open and no more problem the next couple days we were there.
Apparently was a ground dwelling type of pack rat there that did all the damage under the hood in the dark.