Abs light due to poor electrical ground under the battery tray on gmc sierra 1500 problem description a poor electrical ground under the battery tray may cause the abs warning light to illuminate. Your gmc sierras abs light comes on when it fails a self diagnostic cycle when on it indicates that the sierra does not have anti lock brakes and the safety they provide your sierras abs system uses a system of sensors to determine wheel speed when braking. This is a very common problem on the early 2000 gmc trucks it affects the tahoe suburban yukon silverado sierra bravado jimmy blazer sonoma s10 and. 2001 gmc sierra abs light problem 2 answers today i turned my truck on and the abs light came in driving home abs kept engaging replaced one of the abs sensors and the light will now come on a start up go away them come back when i get up