Assist Step Controller Disable Switch
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The disable switch input is normally pulled to B+ through a resistor in the assist step controller. The disable switch sends a ground signal to the assist step controller with a switch closure. The assist steps will move to a retract position once all doors are closed and remain retracted until the disable switch is opened and a door on the same side as the retracted assist step is opened. An assist step that is extended when the disable switch is active will retract when the vehicle speed reaches 5 mph or the vehicle is shifted from the park position to the drive position.