I also had a problem with ABS and brake warning light staying on after the engine was running. Normally they come on briefly when you first turn the key, then go out after the engine starts. Everything else seemed to worked fine including speedometer, cruise control and brakes. (I have to assume the antilocks would not have functioned properly but did not test this since I haul a camper around)
I ohmed out the rear wheel speed sensor located on top of the rear differential. It was open or I could say that it read infinite ohms. I got a new rear wheel speed sensor from the dealership for around 34 dollars and it read a little over 1800 ohms. After installing it, I started the truck and the lights still stayed on. I backed out of my drive and after around 30 feet of forward motion the lights went out.
The tools I needed were wire cutters for cutting tye wrap, 1/2 inch and 9/16 inch socket for removing the nut on the stud, then the stud itself. Also need a new tye wrap.
Cheers!
I have a 2000 Dodge CTD with antilock on all four.