4WD Control Module
WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
The 4WD control module, integral to the PCM, controls the operation of the transfer case in response to the inputs from the shift motor, MSS, BOO switch, digital TR sensor, throttle position output from the PCM, stability assist module (if equipped) and the VSS.