Rear Power Window Lockout Operation (RPO A31/AN3/DL3)
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 BCM monitors the window lockout command from the DDS. When the rear window switch operation is authorized, the BCM sends a signal to the rear window switches allowing for normal window operation from the rear switches. If the rear window lockout function is commanded, the BCM signal voltage drops approximately 5 volts which disables the rear window switches and the rear windows will only operate when the BCM receives a command from the driver master control. The lockout feature will remain in effect until the ignition switch is cycled or the driver enables the rear windows by pressing the rear window lockout switch again.