July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!
Possible Causes
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.
circuit 972 (BK/WH)
circuit 1203 (BK/LB)
4WD control module
circuit 693 (OG)
Fig 1: Pinpoint Test A: No Communication With The Four-Wheel Drive (4WD) Control Module (Step A1)
Courtesy of FORD MOTOR CO.
Fig 2: Pinpoint Test A: No Communication With The Four-Wheel Drive (4WD) Control Module (Steps A1 Cont. & A2)