Conditions for Setting the DTC
WARNING: This page is about a different car, the 2009 GMC 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 ignition voltage available to the EBCM is less than 9 V for 100 msec.