Have mine in the Tranny shop right now for the same reason,Tech found a snap ring that holds what I would call a servo plate for the over-drive was off.My truck wasn't pulling at the time it started the problem,just running it hard.Acted like it came out of over-drive ,but when i slowed down ,saw that beepbthe O.D. was still off.I tried the button and the tranny shifted out of O.D.The tech told me that this plate/servo I call it, will reposition its self until under a load agian.I tried like hell to get to do it again,but couldn't.Truck only has 88,000 on it,but I wanted to know what was up and to upgrade-T.C. valve body and eletronics.I went ahead with a Banks 6 gun and I'm adding a tran-temp gage also.Good luck with yours, mine should be out Wednesday.Mike