05 Silverado 4wd issues

[chevyrider102.2]

My 05 Silverado 1500 has been having some 4wd issues, the fuse in the truck is good, and apparently I don’t have a Trec or ATC fuse under the hood. When I start the truck all of the shifter lights come on, but some days none will come on, or the neutral one will come on, but’s it’s always in 2wd. I haven’t tried shifting it into 4wd because it’s has not been very reliable.
I swapped out a new switch and started the truck, and no lights came on after they all flashed. I freshened up the ground that’s underneath the drivers side, and replaced the front actuator, what else could it be?
Thanks

 

[zora]

The system uses a control module. The correct way to start determining the cause is to scan it for errors.