99 4x4 stuck in 4x4hi

I have a 99 gmc sierra (new body styl) z71 with the 5.3l and push button selector switch for the four wheel drive. I recently noticed the truck was starting to shift hard. Last time it did this I switched into 4hi then back to 2hi and it went away...this time when I switched into 4hi it didnt want to switch back into 2hi or even auto 4x...Normally the light blinks when it is trying to switch but its doesnt look like it is even trying! the indicator light does nothing...


the light does turn on when you start the truck....so I know its not burnt out


anyhelp would be sweet!