Ford F-150 Cruise Control

I have an F-150 Ford pick-up. While driving on cruise control it will shut itself of sometimes, and it won't re-engage.

I did a self-diagnostics on it and the cruise control light flashes for each button pressed as required. When the sequence is completed, the throttle pedal gives a flip, and then it will work again for a short time. Today, however. at the end of the sequence of the self test, it flashed the cruise light three times. That's supposed to indicate a brake pressure control valve defective circuity.

Any thoughts? Are we talking about replacing a brake switch or what?

Thanks for your help!