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.
The control module detects that the commanded state of the malfunction indicator lamp (MIL) driver and the actual state of the MIL control circuit do not match for greater than 3 seconds.