4x4 auto engaging/grinding

[skitzotic]

first the 4x4 light stays on most the time, but when it actually goes off a lil bump or turn will make the 4x4 try to engage but it can only go bout half way im guessin cuz the shifter (shifter on the floor not push button) isnt engaged it starts grindin if i shift it into 4x4 it goes away then i can put it right back in 2x4 position, 4x4 light stays on but transfer case shifts out of 4x4, btw 95 Sierra K1500, btw the 4x4 is manual shift not servo controlled, has a direct linkage

[chevyguy]

Sounds like the actuator on the front differential is ginving you fits. Or it could be the switch that engages the actuator.