This is a slightly different system than your trailer brakes. With the trailer brakes, the controller you have installed in your vehicle allow you to adjust how much and when you want to apply them. This thing is in the event of the trailer coming disconnected from the tow vehicle. The cable that comes out if it (which looks like it needs to be replaced) connects to your tow vehicle and in the event of a break away, the cable should pull out that little round key on the end. This causes a connection to take place inside this box, activating the electric trailer brakes using the power from the trailer battery on the tongue.

Yeah, this was explained to me and I agree it look pretty shot. Do you know how I would go abut getting it replaced?

If the switch itself looks clean inside, you could just spend maybe $5.95 on a new key/cable assembly. Otherwise you could get the whole switch assembly and have to wire it in.

How do I check the switch inside? I see a bolt that attached it to the hitch but no screws or anything to access the inside.

Yeah, that would be difficult. I guess maybe just some sandpaper on a nail or screwdriver to clean off the contacts. I don't think there's a good way to check it without just cleaning it. Make sure to not have a battery connected when you do that so you aren't sending sudden power surges to the brakes.

Yeah, I have not even gotten a battery yet. So that much won't be a problem. I do have sandpaper around. I'm DIY type of person with an inventory of tools and supplies. It is on my to-do list to find out what kind I would need and case for it along with a cover for the propane tank as well.

For a trailer like this, just about any RV/Marine style Group 24 battery will do the trick. Some people go with group 27 batteries which are larger and offer longer lasting power when off the grid. Some also go the route of two 6 volt golf cart batteries too, wired together. That gives you some real long term power, a good few days without needing a charge. If you plan to be out off the grid camping, then that's (an expensive) thing to look into, but if not, then a group 24 will be more than adequate. The cases are made for the size battery, and they usually come with the hold down strap.

Good little safety feature. Mine has this too. Of course, it's on the list of items to be tested and checked.

With out a camper battery the safety switch will not work. Pull the cable as long as you have a camper battery the camper brakes should lock.