I have a 1996 ChevCK 4wd truck. all of a sudden when I shift to 4 wheel drive high range or low range, the lever moves to the proper place but there is no hook up of the front wheels, also the indicator light on the tunnel by the shift lever dosnt light. An idea wher I should begin looking? Thanks for any help.

 

I'm not diagnosing your problem 100%,but I know these trucks have an isssue with an actuator,check this out.....

https://chevroletforum.com/m_82836/tm.htm