One problem related to headlights turn off while driving has been reported for the 1999 Ford F-150. The most recently reported issues are listed below.
Approximately two weeks ago (10/2014) I noticed that the headlights on my 1999 Ford F-150 were not working. A few times once I returned to home I noticed that when I shifted the truck into park, the headlights came on. It did not appear to matter if the high beam or low beam lights were activated. I started to inspect the headlight operation and noticed that when I tilted the steering wheel to it's lowest position, typically it's operating position, the headlights turned off. When I tilted the wheel up slightly to the next position, the headlights would come on. Today, 10/19/2014 I removed the trim around the steering column and noticed that there are two wires that have broken and separated from the wiring harnesses that attach to the turn signal assembly and several contacts that are loose in the upper harness. I have taken photos and a video showing the parts that are loose and or broken. Because these broken wires and contacts are loose and affect the operation of the headlights, I am concerned about the risk of a short or sparks that they could create and without fully operational headlights, the vehicle is not drivable. I am the second owner of the truck and purchased it at around 11,000 miles. The steering column has never been taken apart nor has the trim around the steering column been removed. These wires could be seen moving as the steering wheel was tilted up and down prior to the signal assembly being removed as the headlights turned on and off with the light switch left in the on position.