Whats up everyone, let me start by saying i'm like car stupid other than minor things. Okay so i've had my 2000 jimmy for 3 years when i first bought it the 4x4 worked fine. i have never had a reason to use it until today. i've got 2 wheel, 4 hi, and 4 lo buttons. When i get the 4 hi and 4 lo buttons my car makes my thumping sound sound and the car jerks. the light stays on for which ever mode i push but the front wheels will not spin. A guy at my work told me when we get better whether to get going around 40-50 mph and turn on my 4 hi and that should get it to work. So my question is whats thumping and why is my car jerking foward but not locking the front wheels? like i said i'm car stupid other than oil changes and minor stuff like that.

Thanks in advance.

 

Read the stickies and search.....tons of threads about this.