[Puffnstuff]

Well I'm no expert and it's been a while since I've had a 4x4 but if power isn't making it to the front wheels then your problem is with the transfer case. I don't know what that autotrac case looks like but if it autotrac portion is not external then it sounds like you need to open it up and check the internal linkages. You didn't say whether or not the truck was actually in 4wd when the dash indicator was lit but the service light does indicate that there's something wrong enough in there to trip the logic. You would probably get a better answer if you were to post this in a truck forum like over at pickuptruck.com.