Our family's Suburban has 250,000 miles on it and has been taken for service regularly but its been acting very funny for about the last 60k. The push button 4wd system has a mind of its own. Sometimes it will engage 4 low and then lock itself there so we can't get it our without restarting it. Other times it goes into 4wd auto mode or into the Neutral zone. And then we have to do the same thing and restart the car. Other times we attempt to shift into drive and there is a loud clang or metal and its a bit worrying. There is definitely a slow leak from the rear diff because we have to top it off every once in a while. Other than that the 4WD service needed light comes on. But we just had it serviced at 200k. I'm not sure what to make of this. Thanks for the help in advanced

 

the clang is possibly a ujoint and the leak you'll just have to look for, as far as the 4wd you'll need to get the code itd be tough to be accurate online with that high of mileage