4x4 works but when i took it out of 4x4 mode then into reverse it made a real loud grinding noise. It's a 2007 with 18000 miles. I don't use the 4x4 much and not for driving only for pulling up steep hills for very short distances, less than 200 feet. Could it be something that messed up on it's own or maybe I did it. What could be the problem? I'm gonna take it in for them to check it out but I want to have an idea if what they tell me is a load of BS since they tend to lie to women.

Did it "clunk" at all? Did it grind for a quick second and go away or did you have to put it in another gear for the grinding to stop?

it grinded for a little bit when a put it in reverse

It sounds like the transfer case didn't switch all the way. I'm guessing it is an electric shift on the dash? If so, if the 4wd light is flashing it hasn't switch out of 4wd and could explain the sound.