Four Wheel Drive (4WD) Low Switch
WARNING: This page is about a different car, the 2007 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
The four wheel drive (4WD) low range switch is located on the transfer case cover. It provides an indication of when the 4WD transfer case gear system is in the low range. The PCM then modifies the shift schedule for 4WD low transfer case gear ratio.