One problem related to brake abs warning light has been reported for the 1999 GMC C1500. The most recently reported issues are listed below.
Abs motor started running loadly continuously. Abs light on. Had to have motor disconnected, so don't have abs now. Our mechanic said he has seen several 1999-2000 GMC/Chevrolet trucks with this problem. We contacted general motors; they said there is no recall, truck out of warranty, it's our problem. We are told it will cost approx. $1300 for repair. We believe it is a manufacturer/safety defect.