Oldsmobile/Buick Repair: GMC 4x4 problems, gmc 4x4, axle shafts

Question
I have a 1994 k1500 GMC with a 6 cll engine. Lately, when I put it in 4WD position, the 4x4 lights dont come on and the truck doesnt go into 4WD mode. I dont use 4WD very often but need it occasionally. I have not tried any fixes. The truck has had no major repairs but does get regular maintenance.

Answer
Hi Joe,
The most common 4X4 problem with GM's, is the front axle actuator, which engages the axle shafts, and turns on the light.
The transfer case has a switch that when in 4 wheel drive, sends power to that actuator.
There is a fuse also, but I'd bet on the actuator.
Van