Circuit/System Description
WARNING: This page is about a different car, the 2008 Pontiac G8. However, it is still accessible from the selected car via links, so may be relevant.
The priority key selection test is performed using the scan tool, and checks for correct switching between the Priority Key 1 audio system settings and the Priority Key 2 settings. Note that when the priority key selection is made at the scan tool, the audio system responds to the change then reverts back to the selection corresponding to the key in the ignition.