Hi, I have a 2005 GMC Yukon that placed itself in 4 LO a few days ago. It took a few attempts to get it back in 2 HI and luckily we were in a parking lot when it happened. After this the "Service 4WD" message was on the info bar on the dash. I took it to the local Checy dealer this morning guy checked for codes there were none and none in history. I have read various posts on websites etc. About the encoder motor, sensor, the 4WD selector switches, and wiring harness to the transfer all being fairly common problems. Anyone have any thoughts or best course of action here? I am afraid it could happen again on the interstate or something which would be VERY BAD for the transfer and trans.