Conditions for Setting the DTC: P0573
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The ECM detects a high voltage signal on the stop lamp switch signal circuit for more than 2 seconds when the serial data message from the BCM indicates the brakes are released. The ECM sets the DTC when the condition has been detected 8 out of 10 times.