Conditions for Setting the DTC

WARNING: This page is about a different car, the 2007 GMC Sierra, 2007 GMC Cab & Chassis Sierra, 2007 Chevrolet Silverado, and 2007 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

IAH battery voltage is more than 16 volts.
The GPCM battery voltage is between 8-16 volts.