Not assigned in the generic OBD-II standard - if your scan tool shows this code, it is manufacturer-specific; verify the meaning in your make's service information

C0561 (ABS disabled) on GM trucks is an informational code -- it means ABS is disabled due to another code. Do not chase C0561 directly. Pull all ABS codes and fix the primary one (often C0035, C0040 wheel speed sensors, or C0161 brake switch). Once the primary code is cleared, C0561 clears itself. A common rookie mistake is replacing the EBCM for C0561 when the real problem was a $20 wheel speed sensor.

Trailblazer C0561 is a pointer code -- it rides along with the real fault. Use a scan tool that reads ABS codes to get the full list. Most commonly the primary code is C0035 (front wheel speed sensor) or a C0110-series pump motor issue. Fix the primary first, then C0561 goes away. Bleeding the ABS is not needed unless the hydraulic unit was opened.

Impala C0561 almost never stands alone. It means the EBCM has disabled ABS for safety because of another fault. Read all ABS codes with an enhanced scan tool, address the primary code (commonly a wheel speed sensor), then clear all codes. C0561 disappears once the underlying problem is gone.