my truck wont go into 4x4. the lever goes but no light comes on or the wheels don't ingage. anything!!!!

 

Check the lines coming from the transfer case to the front axle ( assuming it has the front axle disconnect !?)that they are hooked up and no breakes in them , then check to make sure that there is vacuum going to one of them when trying to engage 4x4, and the other when out of 4x4. If that is all good, remove the actuator at the front axle disconnect and make sure it can move when there is vacuum applied to either side of it. If it can move with vacuum it should go into 4x4. You can also unplug the switch on the opposite end of the actuator and jumper the two wires together to make sure the bulb and circuit is o.k. for the 4x4 lamp.

 

Sometimes it won't engage until the truck moves a bit forward or backward. Are you trying to move after shifting into 4x ? If yes, then like Vzdude said, vacuum problem or actuator is binding.
-P