On my 2003 chev 2500 my abs and emergency brake light keep going on and off along with the dinger, anoying. Was told to swap the three sensors around on my transfer case problem still persists. Not even the mechanics at my local GM dealer can tell me which of the three sensors is the rear wheel speed sensor. Maybe it is a frayed wire being that it started after I got stuck in the mud but its tuff to find problem when no one can tell me which sensor it is. Yes I had a code reader on it and it said rear wheel speed sensor
abs and emergency brake light go on and off on 2003 Chevrolet Silverado 2500
if your 'mechanics' at the dealer don't know which sensor it is, you really NEED a new dealer. the sensors are located a specific order. uses a data scan to see which one is not working: go here for the info:
Change the abs sensors (2) in the front of the truck. You can try to clean them but they usually break.
The answer to this is a conection under the fuse box that is loose.