Perplexed??? Need A Master's Help

[GeoffA]

George, feel free to chime in too :nah:...

Yesterday me and the Family drove from Lockport NY to Indian Trail NC in the wife's Trailblazer. Just as we were leaving PA I stopped and filled up with gas. About 5 minutes later the service 4 wheel drive warning light lit up and stayed lit. It did not seem to drive any different and NO i was not driving in 4x4 on any portion of this trip. Average speed 75mph the whole trip +- 10mph at times. And was averaging 20.2 mpg's.

I did stop to rest for about an hour, and upon start up the light was still on. I ended up driving with the light on for approx 450 miles. At no time did I turn on the 4x4 to even check if it was working and still have not. When I woke up around noon (the truck sat for around 8 hours) I started her up and the light was not on? I went to AutoZone for a scan, and no codes were found.

What do you think the problem is/was?

[DQGTO]

Mom has a ummmm i forget the exact year, one of the first few years of the TB, for some reason i am thinking it is a 05? Anyway, that has happened a few times to us and it is nothing to worry about as we were told, I hear that is just a reminder to service the 4 wheel drive for routine maintenance, whatever that may mean. This is where the resident expert comes in. I figured I would post bc I have had it happen and nothing has come of it thats been bad. Our TB has about 110k on it and no problems with the 4 wheel drive ever

[GeoffA]

You mentioned milage, ours is just over 30,000...

[DQGTO]

Yeah but this has happened a few times and if my memory serves me correctly it was in low mileage as well. Read the owners manual quick and see where it talks about the recommended services for the truck and it may tell you at 30K or 50K or whatever the number is, to get the 4wd serviced or checked etc. I think it is honestly more of an "idiot light" to remind people about the forgotten 4wd. Obviously you did the right thing by checking for codes and etc but I would have it checked out just in case, never know if something could have went in the transfer case etc

[GRRRR8]

This is more common then you would believe on ALL GM all-wheel drive/4WD vehicles. It has a issue with the transfer case control module. Sometimes its a simple as a reflash, sometimes it has to be replaced. I had a 04 Z71 Tahoe with 1100 miles on it and was 800 miles from and it did the same exact thing after stopping for gas. They replaced and reflashed the module.

[GeoffA]

Thanks to both of you. Now I know what to tell them to look for so they don't reflash the whole car and loose my tune.

Geoff

[GRRRR8]

I would get 5 or 6 a month in when I lived in Georgia and worked right off of 85N. It always seemed the issue would happen after extended driving or freeway driving.

[DQGTO]

yeah it was usually on trips for us as well. Its gotta be the computer acting weird or something when its on for that long.