One or both of the wheel speed sensor harnesses are damaged. Although they are inside a plastic conduit, the wiring can be damaged inside by repeated turns of the steering wheel. A common location for damage is where the harness is crimped with a metal band to hold it in place.
GM makes replacement harnesses (left and right) and are specific to your vehicle (various years, engines, options, etc.).
You can carefully examine each harness and try to determine if there is a break in the wiring (or damage).
If you do a search, there are numerous threads on this forum about the problem.
PS - It is a brake warning, not a break warning.....