Mine does the exact same thing. It runs just fine, just passed emissions and I had a diagnostic check and there were no codes or anything else sighting why. My odometer also goes out every now and then, but I'm assuming both are due to the age of the truck.

 

If the truck acts fine then it could be a bad wheel hub/sensor. And about the odometer in the previous post, a loose connection causes it to go out, mine doesn't work when its hot outside until I hit it.

 

Yupp 90 percent of the time its that. Do what this guy said had same problem with my 2000. It cost about $20 and about 5 mins of work. Than it should go off. To get it read it will prob cost you over $50 so try the rear sensor first. It is known for going out cause mud and stuff gets caked on to it.

 

To the guys with odometer issues. You need to take your cluster out and do a lil bit of soldering. There is a stickie on here. Check into it if you want yours fixed. That is a issue with 99 and 00 models not sure about newer models I have a 03 now and my gpa has a 02 and neither do it. So i think its just 99 and 00.

Here's a how to on f150online.

http://www.f150online.com/forums/art...er-repair.html