C1256: OBD-II code C1256 flags a secondary internal fault inside the EBCM — the module's self-test detected a problem in a different internal region than C1255.

Symptoms

• ABS, traction control, and stability control warning lamps illuminate together and remain on continuously after every start.
• ABS, traction, and stability interventions are disabled while the code is active; standard hydraulic braking is unaffected.
• The code often will not clear until the underlying module fault is corrected — a scan-tool clear returns immediately.

Common causes

• A genuine internal EBCM component failure that the module's diagnostic self-test has detected in a secondary region.
• Low or unstable battery voltage repeatedly tripping the module's internal watchdog into a fault state at start-up.
• A software corruption that in some cases can be resolved with an EBCM reprogramming rather than full replacement.

What to do?

Verify battery voltage is 12.4 V+ at rest and 13.8-14.5 V running — unstable supply masquerades as an internal fault. If voltage is good and C1256 will not clear, the EBCM has failed its self-test and needs replacement or professional rebuild, followed by programming with the vehicle VIN and options.