My lights would come on randomly, but especially when it was raining on my 2001 2500HD and it was the antilock sensor on the front hubs. Do your brakes feel good? This was a while ago and the sensor was not available by itself. I would of had to have replaced the hub as well and they were $180 per side. So I just lived with it.
2003 Chevrolet Tahoe 4X4 5.3
2002 Chevrolet 2500HD 4X4 8.1 - BlackBear Tuned