Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
The most likely cause of DTC C0269 or DTC C0274 is a mechanical failure that causes a wheel to lock and remain locked. The DTCs may also set, conceivably, when the ABS is activated on surfaces that are nearly impossible to get traction on. If the DTC sets within these conditions, diagnosis of the ABS system is not necessary.