The audio steering wheel control switches duplicate the function of the primary controls of the associated component, through a network of multiple momentary contact switches and a series of resistors. The radio supplies voltage to the switches and monitors the return signal for when a switch is pressed, a specific voltage drop occurs. The radio identifies the one selected to activate the feature, otherwise sends a serial data message that is received by the component controlled, activating the feature. With out RPO K59 the body control module (BCM) supplies voltage to the Mute/Seek switches and monitors the return signal, then sends a serial data message as the radio does.

This section is intended to diagnosis the circuits between the radio or BCM and the steering wheel control switches. If the primary control for the device is inoperative, refer to the appropriate section for the component the steering wheel control switch is functioning.