I have a 91 Silverado 5.o litre with the 4x4 shift lever on floor
-Indicator lights for 4 high or 4 low dont come on bulbs are good.
-4x4 25 amp fuse under dash is good,is there another one somewhere.
-In 4 low I can hear it clunk in when shifting from -nuetral to drive but front wheels not turning, rear are.
-In 4 high I dont hear anything
-Truck is acting like 2 wheel drive, slipping all over in the snow. What can I check

 

my 93 has a actuating solenoid down on the front diff, just right of center when looking at it from the back. ive not had trouble with mine but i hear they are a pain.i think they are electrically operated so id be checking if it is receiving any juice when shifted into 4wd. let us know what yu find

 

It was the solonoid I picked one up and installed in half an hour, very easy.............works great now.