Steering Wheel Controls
WARNING: This page is about a different car, the 2007 Cadillac XLR. However, it is still accessible from the selected car via links, so may be relevant.
Some audio functions are available using the steering wheel controls. The steering wheel controls consist of multiple momentary contact switches that connect a series of resistors. When a switch is pressed, a voltage drop occurs in the resistor network, which produces a specific voltage value unique to the switch selected. These specific voltage values allow the CD changer or body control module (BCM) to identify which switch has been pressed. Class 2 messages are then sent from the CD changer or BCM to the appropriate component to perform the desired function.