4x4 Low Switch
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2007 Ford RV Cutaway, 2007 Ford Pickup, 2007 Ford F550 Super Duty, 2007 Ford F450 Super Duty, and 2007 Ford Econoline. However, it is still accessible from the selected car via links, so may be relevant.
The 4x4 low switch provides a signal to the instrument cluster when 4x4 low is selected. This input is used to adjust the shift schedule. Using the controller area network (CAN) (F-Super Duty) the instrument cluster provides a four wheel drive (4WD) status signal to the PCM.