My truck is a 1999 V8 5.4L F-150 FX4 with the electric shift 4WD. I have two problems that I think that they could be related. First off my ABS light turns on solid when i shift to drive and accelerate to about 2 mph any time i drive. My other problem is my 4WD. When I turn my **** to 4WD H or L (of course going to low through neutral) the trucks front wheels will not pull at all. All the 4WD lights in my dash seem to work properly. I have been doing some reading and was wondering if both of these problems could be the result of a faulty VSS sensor. If anyone has any tests I could perform or any advice on how to fix these problems or if someone could tell me if these problems are even related, it would be greatly appreciated.

 

Have that same problem with my F350. The rear speed sensor seems to be the issue that is most common. I changed it twice and it seems to come back. Try to just disconnect and connect back, this helps me sometimes. Did that just today actually. Just my $0.02. It is cheap and doesn't take long. Fairly new to the Ford scene, please don't stone me.

 

For the 4x4problem check these out.
https://www.ford-trucks.com/forums/6...nt-engage.html
https://www.ford-trucks.com/forums/6...-engaging.html
or use this search: https://www.ford-trucks.com/forums/s...earchid=743151

 

I got it fixed my abs was a speed sensor on the top of the rear differential. My 4WD problem was a faulty vacuum actuator motor.