SOP when the service 4wd light comes on is to hook it up to a diagnostic computer and see what fault the 4wd computer is seeing and diagnose from there. Without that step, we'd just be guessing what it might be.
I don't know if the '06 still had the same problem, but it seems that my vintage had issues with the switch, and a lot of people "guess" that the switch is bad and replace it and go on.
I don't know if the '06 still had the same problem, but it seems that my vintage had issues with the switch, and a lot of people "guess" that the switch is bad and replace it and go on.