So selector switch moves to all positions and light doesn't constantly blink or go away.... shows constant on every position. I can hear what I think would be the actuator activating when the switch is moved in all positions. But the front wheels don't "chirp" "grab" like all my other GM vehicles. When in 4 low... it seems like it goes in....you can feel movement that it got into 4 low... but tires don't act like it.... only thing is does is feel like it is geared really low... and stays in like first gear. I even replaced the actuator on inside of passenger side wheel well.... no difference. I got into some gravel and punched the throttle.... front tires didn't turn. Should I be hearing two separate noises?.... from the actuator and the encoder motor? What all parts do I need to look at other than the actuator? I have no service 4wd light on.

Any codes?

no codes. I listened closer today... it sounds like a switch activating... I can hear two distinct sounds when I switch the selector... sounds like the actuator to me. But I'm going to try to get someone to help me... while I listen to see where it'* coming from. I just don't feel the "locking in" feel that I know from every other GM. So I guess I need to get it up on some stands and listen and then see if I can move the front driveshaft?

More testing.

I hear the actuator activating from 2wd to auto. But not from auto to 4HI or 4HI to 4LO. I only hear actuator again going from auto back to 2wd.

I do hear a motor around the transfer case activating in all switch positions.... it'* not too loud.

Sounds like the front axle actuator isn't working. Start the car, engage 4WD (not Auto4WD), drive at least four car lengths, put car in Park, leave running and in 4WD, lift only the right-front wheel off the ground. Attempt to turn the wheel by hand.

Does it turn?

If it does turn, does the front drive shaft turn with it?