Dodge 2004 HB Durango - Manual (Page 210)

4LOCK
Four-Wheel-Drive LOCK - Locks the front and rear
driveshafts together. Forces the front and rear wheels to
rotate at the same speed. Additional traction for loose,
slippery road surfaces only. Shifting Procedure - NV 144 Transfer Case
AWD to 4LOCK or 4LOCK to AWD
With the key ON and the engine either OFF or RUN-
NING, rotate the transfer case switch, located on the
instrument panel to the desired position.
210 STARTING AND OPERATING