Conditions for Setting the DTC
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The glow plug controller detects that the glow plug control circuit is open, shorted to ground, or has more than 1 ohm of resistance.