Start by getting under there and spraying all your suspension components with lubricant and then try it out. Weight distribution hitches have also been known to make noise, so try a quick tow without the bars hooked up.
Is it a factory brake controller or an add on?
2013 F-150 EcoBoost MaxTow
2013 Jay Flight 28BHS Elite
"My wheel lugs require more torque than your Honda makes!"