Ford 2015 F-150 Owner's Manual page 192

For 2WD vehicles
E183740
Turn the control to ON.
Once the indicator light
illuminates in the information
display, both rear wheel axle
E163170
shafts will be locked together providing
added traction.
If the indicator does not come on, or the
indicator turns off while driving, one of the
following has occurred:
• The vehicle speed is too high.
• The left and right rear wheel speed
difference is too high during an
engagement attempt.
• The system has malfunctioned and is
accompanied by CHECK LOCKING
DIFFERENTIAL in the information
display. See your authorized Ford
dealer for assistance.
F-150 (TFC) Canada/United States of America, enUSA, Fourth Printing
Rear Axle
189