Trailer Brake Controller on 05' Ford F250 not working right?

It seems that I remember the early F250/350 controllers would not activate the brakes if you were stopped or if you were traveling under 10 or 15 mph. Sorry I can't remember the year models though. It should be easy to check by visiting the the ford truck forums and doing a search. I am sure someone here will chime in soon enough with the facts as well.