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