There have been multiple posts in multiple threads on this message, but I have yet to find an answer as to what is actually going on in the transfer case to cause this message. I am getting it on my 2005 Sierra (64000 miles,5.3L, 6" lift, 4.56 ratio, 35 inch tires.) It sporratically(sp?) came on about a year ago, about once every 2 weeks. Now it comes on everytime I fire up the truck, and now accompanied by a blank transfer case selector panel. In other words, there is sometimes no light illuminated telling me what position the transfer case is in. Selecting anything is not possible. The truck feels like it is in 2 wheel drive when I drive in it in this condition. The only way to fix the selector panel issue is to completely shut down, wait a few seconds and restart the truck which usually illuminates the 2 wheel drive light and that part of the problem is back to normal. The "service 4 wheel drive" message never goes away, however. If the selector panel is working, I am able to shift in and out of 4 wheel drive still. I hooked up the Superchips programer and it came back with nothing, as in "no trouble codes found". (Piece of Sh!t waste of 300$). Anyone out there have any input on this? I don't want to take it to a dealer and get raped financially. My first guess at this is the selenoid is bad. Help.