Brake-light problems on the Ford Super Duty are caused by one of a few issues. A faulty fuse, faulty wiring at the housing terminal and a blown bulb are the most common problems. Occasionally, the brake light switch might fail. However, before you go replacing parts, troubleshoot the problem first.
Check the fuse. This is always the first thing you should do when troubleshooting brake light problems. Remove the fuse panel below the steering wheel by pulling it down. Some F-series Super Duty trucks have a release latch you must lift up on to remove the fuse panel cover. Remove the fuse for the brake lights using the fuse puller on the fuse cover. Use the fuse diagram to locate the fuse for the brake lights. If the fuse is blown, replace it with a fuse of the same amperage.
Check the brake light bulbs. Bulbs do blow out, so check them every six months. The easiest way to check the bulbs is to turn on the headlights.