Conditions for Setting the DTC
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The EBCM detects that the voltage supplied to the valve solenoids is less than 80% of monitored ignition voltage for 50 milliseconds.