Problem with 4LO light blinking when truck is not in 4WD.

What is your question?

I travel roughly 100miles at highway speeds every day and even on dry pavement my 4LO light blinks constantly. We recently had a snowy day and I put the truck into 4HI but the indicator light on the dash that shows you've locked into 4WD would sometimes show me locked in, and sometimes not. I have also been experiencing a very strong vibration traveling at any speed coming from the Front wheels. Getting an estimate done this weekend (non dealer), but I am curious as to what you guys might think is going on. Thanks