Detection / Analysis Of Miscellaneous Body Switches
WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
The BCM detects the position of the A/C Switch from the control head and reports this over the PCI bus to the PCM.
The BCM detects the position of the Renegade Lighting Input and reports this over the PCI bus to the Cluster.