Brake controler problem

[Berge9798]

I have a 99 F350 and i have been having a problem with the brake controler. When i push on the brake pedal it does not work the trailer brakes but if i Sqeeze the over ride bar on the controler the brakes on the trailer will work. Also if i have the setting on the controler to high and i sqeeze the over ride the breaks will some times stop working and the light on the controler will go off and i have to pull over and unplug the connector from the truck to the trailer and then they will start working then. I know its not the trailer because they work fine on my other trucks. any ideas what the problem could be?

[KnockingDiesel]

How old is the controller and how many axles on the trailer. Some brakes controllers have like a thermal shut down and if they are in dusty conditions their service life is 1 to 2 years max.