I have a 2004 Chevy Tahoe and today it just stopped shifting into overdrive. I noticed that it didn't start slipping it just all of the sudden stopped going into overdrive. Therefore I'm thinking that it's not the clutches but I am leaning more toward the shift solenoid not working. I can shift manually from 1 to 2 to 3 then overdrive but when I shift into overdrive it doesn't actually go into overdrive it stays in 3rd and runs 45 to 50 mph at 3500 rpm so I'm leaning more toward the solenoid and I'm just looking for input if anyone has had this problem and what their fix was.