The SSS light comes on when there is an error detected in the ABS system. Most often for our cars it is due to a bad wheel speed sensor, but it can also be a steering wheel position sensor, a yaw sensor, the electronic brake control module and a couple other things I can't think of right now. Justin'* advice is absolutely correct. You need to have the car scanned for diagnostic trouble codes, but the scanner must be capable of reading ABS codes. The scanners they use at Autozone don't do that. You need to go to a shop with a Tech 2 scanner. You could try a good transmission shop. Scanners that will read transmission codes will probably also read ABS codes. Once you have the code it should lead you to the failed component. If you have the code and need help interpreting it, let us know. If you know what needs to be replaced and want to know how to do it, let us know.
Once you get this fixed, please let us know what the issue was. It helps us assist other members with the same problem.
2001 Bonneville SSEi (retired at 365,000 Kms.)
2014 Jeep Grand Cherokee Overland (yes, I know its not a GM)