Pinpoint Test M: The Ambient Lighting Is Inoperative - MKZ: Notes
WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, and 2011 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
Refer to SYSTEM WIRING DIAGRAMS article, Interior Lamps for schematic and connector information.