1998 F150 - with 123k miles and not a 4x4. My ABS light came on this afternoon going down the highway and stayed on till I got to work. On the way home it was off for about 5 miles and then came back on. Any advice on what this could be would be great.

 

Check the ABS sensors on the back side of each brake rotor. Also check the sensor rings for damage or rust/mud build up.(they look like gears, with teeth around the perimeter). Sometimes the sensor (s) is good, and the 2 wire harness has been either damaged or unplugged.

Dave

 

since the lilght was off at startup, the computer is seeing a good circuit. If the light comes on as soon as you start moving, then the speed pickup is not sending a signal. if the light comes on several miles later, normally the oil is dirty or the speed ppickup end is dirty and not getting a constant good signal. Our EXP did this. I took the pickup out of the rear pumpkin, cleand the end off, reinstalled and it worked for 1 year. Eventually i needed to get a new pickup. IT worked, but weak signal.