Circuit/System Description
WARNING: This page is about a different car, the 2008 Cadillac XLR. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) supplies voltage to the MUTE/SEEK + multiple momentary contact switch and monitors the steering wheel control 2 signal circuit. Each switch state is associated with a set resistance value and when the switch is pressed, a specific voltage drops across the resistor unique to that switch. The BCM identifies the selection and sends a serial data message to the component controlled by the switch activating the feature.