I used it a couple of times,but only for the truck and not the RV. Be sure you have the settings correct. I do know that the height only goes up to 13 feet clearance, so that is very bad if you have a taller RV as I do. Any GPS will have some problems, but they should not be that serious. Like I said check your settings. By the way, how did you get across the bridge that did not exist.
One time before GPS my wife and I were following a map where the road led into the water. We did not realize this until we got near that area. We thought the map was in error, but found out there was a ferry that took you across, not noted on the map.