Conditions for Setting the DTC

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The BCM monitors a dimming return voltage of less than 4.5 volts.
The BCM monitors a 5 volt reference voltage of greater than 5.5 volts.
The BCM monitors dimming input voltage of equal or greater than 4.86 volts for more than 1 second.