Locking Differential not responding

[OttoWisner]

So I have been trying to lock the rear differential on my ZR2 and the light on the switch is not coming on to indicate if it is working or not. I know it worked when I bought the truck in December because the dealer and I went through the whole vehicle. I haven't needed to lock the differential since then until I was in some deep snow the other day. I am curious if I am doing something wrong at this point. I have gone through the owners manual and looked all over the internet and I believe I am activating the system properly. I am attempting to lock the differential while the vehicle is stationary, in park, and in neutral. Its my understanding that I should be able to lock the rear differential when the vehicle is stationary in 2 high, 4 high, and 4 low, but if I am wrong about that please let me know.

The truck also had some electrical issues that the dealer fixed a couple of weeks ago and I am wondering if maybe a fuse blew during all their testing but can't figure out which fuse is for the differentials. If you know which fuse it may be please again let me know.

Any input would be very much appreciated. Thanks!!!

 

[BigSky]

Not in 2x4.

 

[Diesel328]

Not in 2x4.

Mine works in only 2x4.

 

[OttoWisner]

Not in 2x4.

Regardless it the button does not light up to signal that the differential is locked in any of the transfer case modes. Could I be doing something wrong?