4wd light stays on all the time

my 2000 1/2 ton chevy did that for a very long time but i traded it for the 06 LBZ before i figured it out.

There should be a fuse for the 4WD, try pulling it out for a couple of minutes and re-installing it. I know my 2001 half-ton had the switch go out on it, but I would get a service 4wd message and the lights wouldn't come on...it's worth a shot though. You might also want to crawl under and see if you have any shorted or broken wires to the encoder motor.

It is either the ground wire on the frame. Or the selector switch itself. Good Luck.

most likely it is the push button control panel went bad,I had it happen on my 99 twice they are about 80 bucks