I think it's a connector for running lights. Am I right?
I noticed it hanging down inside the front wheel well. Looking into it, I noticed another one on the other side attached to the wheel well skirt.

 

This looks like wheel speed sensor. Let me guess? You have an ABS light on and you ABS does not work. This needs to be plugged in for you ABS and traction control to function.

 

No lights on and everything works fine. In the second pic you can see that it attaches to the fender skirt. I found two more under the front bumber where fog lights would be. I'm thinking the first ones are for running lights on the step rails. Maybe?