Pinpoint Test A: No Communication With the Four Wheel Drive (4WD) Control Module (PCM): Notes
WARNING: This page is about a different car, the 2007 Lincoln Mark LT and 2007 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
Refer to appropriate WIRING DIAGRAM ARTICLE, Four-Wheel Drive Systems for schematic and connector information.