Oh yeah I did that too. It didn't change anything unfortunately. It's just one of those things that's driving me insane. Because I've had 5 of these trucks and this is the only one that's been like this. I've had an 01 Yukon XL, two 04 Suburban's, 04 Sierra and now this 03 Suburban. Every other one had the same kind of mileage except my 04 Z71 Burb had 330k. They all drove great and had no issues like this. It's just super strange that I'll throw it in auto 4wd or 4lo and start driving and it pops up service 4wd but in auto 4wd it'll drive and shift just fine. In 4lo it won't shift. 4hi it doesn't throw the message and is just fine. When service 4wd comes up, it won't let me change the selection. I have to shut the truck off and turn it back on and then I can switch it. And when I go in 4hi or 4lo you can hear it switch and clunk and switching back to 2hi from 4hi or lo you can hear it switch and clunk again. Putting in auto 4wd you don't hear anything