WARNING: This page is about a different car, the 2003 Lincoln Aviator. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Pinpoint Test C: The Four-Wheel Drive (4WD) Control Module Does Not Respond To The Diagnostic Tool (Steps C1-C4)
Courtesy of FORD MOTOR CO.
Fig 2: Pinpoint Test C: The Four-Wheel Drive (4WD) Control Module Does Not Respond To The Diagnostic Tool (Steps C5-C7)