06 GMC Sierra "service 4wd" message.

About two weeks ago I put my truck into 4wd. Was in some sand, nothing big. Was very easy on the truck. Since then the "Service 4wd message keeps coming on. Now tonight, got into some mud and the 4x4 push buttons didnt work. Hit the 4w hi, 4w low, auto, nothing worked!! When i hit the buttons I listened to hear if it engaged and nothing. The buttons didnt light up like it was trying to switch to 4x4, they just didnt work.

The truck has never been driven hard or done any hardcore offroading!

Did research and found a guy with similar problem (but no specifics about buttons) and his problem was the Encoder switch..

Since the "Service 4wd message" keeps coming up, is that a safety precaution mechanism that doesn't allow the 4x4 to engage until you get it serviced?

Any advice is welcome and appreciated. Thanks

Correct, plus it is telling it won't work, careful here just don't throw parts at it without a proper diagnosis, have it scanned with a professional scanner to see what is going on. Dash switches were an issue also.

Well lastnight while driving home, I noticed the indicator light for 2wd hi light was red and is usually orange. Not sure if that means anything!! This morning I got into my truck and it was orange again, i tried putting it into 4wd hi and it worked, so did 4wd low and auto. While driving to my a friends house got the "service 4wd" message again. Got to his house and tried switching to 4wd and nothing happened. Turned truck off then restarted it, and was able to switch it into 4wd again. Put the truck in gear and 4wd low and high work fine.

I have read alot of threads on similar problems and what I think now is just maybe low transfer case fluid or it dirty and needs to be changed??

The truck does have 76,000 miles on it and the the trans case fluid has never been changed or checked.

Sorry for the long post but trying to get every detail in for an accurate response.

hi i m new user here my ist post

UPDATE!!

Had my transfer case fluid changed today and NO "service 4wd" message has came up yet. Goes into 4wd easy and with less of a "clank" noise.