What is most likely wrong with my Ford F-150 XLT truck?

What can I do or what is wrong with my Ford F-150 truck? Last night as I had my truck in reverse, and was backing to the left, my ABS and Brake lights both came on and stayed on for the duration of my trip home. The truck feels like it is refusing to turn left now as well. I didn't hear any type of noise that would indicate that something broke free. While driving it I did notice that as long as it was in some motion with no braking being applied it would turn a little easier, but as soon as brakes were applied it would not want to turn left at all. Does this mean that a brake is damaged?