To add to this (I accidentally used an old account here - sorry, mods), this all assumes the wheel speed sensor is, in fact, the problem. geswek makes a great point that the problem could be caused by the lift install and an issue with wiring. I agree that you should take a good look at everything before going to ask for parts from the dealer. One of the things I noticed on my lift is the guys that installed it did NOT replace some of the plastic wire restraints on the rear axle after the lift. At first I thought it was an oversight but I realized later it was probably intentional to leave more slack in the wiring to account for the lift. You may want to verify none of your wires have pulled loose from the additional distance between your frame and the wiring going to the rear diff.