The AXLE LOCK switch is located on the instrument panel (to the right of the steering column).

Axle Lock Switch Panel
This feature will only activate when the following conditions are met:
To activate the system, push the AXLE LOCK switch down to lock the rear axle only (the “REAR ONLY” will illuminate), push the switch up to lock the front axle and rear axle (the “FRONT + REAR” will illuminate). When the rear axle is locked, pushing the bottom of switch again will lock or unlock the front axle.
NOTE:
The indicator lights will flash until the axles are fully locked or unlocked.
To unlock the axles, push the AXLE LOCK OFF button.
Axle lock will disengage if the vehicle is taken out of 4WD Low, or the ignition switch is turned to the OFF position.
The axle lock disengages at speeds above 30 mph (48 km/h), and will automatically re-lock once vehicle speed is less than 10 mph (16 km/h).
Trac-Lok Rear Axle — If Equipped
Axle Lock (Tru-Lok) Rear Only — If Equipped