One problem related to brake master cylinder has been reported for the 2014 Ford F-550. The most recently reported issues are listed below.
Brake pedal seemed soft when driving this RV (on a 2014 Ford f53) to storage yard. Four hours after parking, I started the RV to adjust its location and the brake pedal immediately went to the floor. There was no other symptom of trouble, no warning message. Immediately after that, the message center on the dash board warned of ¿low brake fluid¿. We are lucky this happened in the storage yard and not on the road. Ford dealer fixed it under warranty, stating that the relief valve in the brake master cylinder had failed.