Body Control Module (BCM)
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The BCM maintains the PTO factory default mode, unless it is reprogrammed with a scan tool to change the PTO configuration mode from factory preset to either stationary variable or mobile variable. The BCM also controls the remote start function. The BCM also controls the illumination of the background text of the PTO switch through the dimming circuit.