In order to activate the axle lock you must first shift into 4L (4wd low). Once in 4L, press the switch once to lock the rear axle, a second time to also lock the front. Pressing the switch a third...
August 1, 1941 <-- this is the year the original Jeeps came out GP actually.However the Rubicon and a LOT of other jeep information can be found here.http://en.wikipedia.org/wiki/Jeep_Wrangler