Validating/Invalidating your warrant is not a black-n-white issue; it depends on degree.  If you (or your husband) were to break the light fixture while removing it, or yanked on the wiring and pulled it out of the walls, or pulled down the ceiling, then - yes - you would have to pay out of pocket for the damage you had done.  On the other hand, if you carefully remove the fixture to inspect the connections and replaced it without causing any damage, then no.  And, of course, there could be several people's opinions (including yours, your dealership's, and Forest River's) as to whether you actually caused any damage while inspecting the fixture; and Forest River will likely lean on the dealership's interpretation and then follow their own interests.

But, frankly, on a brand new trailer, its likely a break in the wire somewhere behind the wall (perhaps a kink, or a screw through it) and I'd suggest letting your dealer fix it.

As you have a brand new trailer, still under warranty, I suggest that you take it on a good shakedown cruise.  Its normal, and should be expected, that there will be some minor issues with your new trailer (regardless of manufacturer).  Bring along a notebook, and the first thing you write in it will be that the light doesn't work.  Test out everything in the trailer (furnace, water heater, A/C, fridge, etc).  Check all the windows, doors, drawers, latches, etc (do they open/close properly? do they stick or rub against the frame? are they installed straight?).  Have a good look at the fit and finish (is the trim on straight?).  Write down anything you may come across, no matter how small.  You may well end up with a list of a dozen or more issues - mostly minor, most of which you feel that you could probably live with or just fix yourself (but really, you shouldn't have to, 'cause its a new trailer).  When you get back from your shakedown trip, book an appointment with your dealership to have these issues addressed.  This is part of the service you've bought with your new trailer and you won't have to fight to have this work done; warranty work is also one of the ways your dealership makes money, so they'll be very happy to see you.

After looking around for a new camper that we could take on the road (we have a 32 footer on a seasonal site but still enjoy trying out other campgrounds) I decided on a 182G since it has the outside "kitchen" for my hubby, and our new baby was delivered yesterday.  My grandson and I spent the night in it last night to "try it out" before actually taking it on the road.

Everything works fine except ONE light, the first one on the ceiling as you come into the pod.  My husband said he could look at it to see if it's a loose wire but my question is this: is it worth doing it ourselves or should we contact the dealer, basically would it null the warranty if we do it ourselves.  

We'd rather not have to take it back to the dealer since we are about an hour away from there.

I know you all have great ideas and knowledge on all types of things on this forum (I read lots of posts before actually deciding to purchase my Lily Pad) so I hope to get your thoughts.

Thanks!