4wheel hi engages by it's self

[charliep25]

i have 2001 yukon with push button 4wheel drive and my four wheel drive engages by itself and i can almost never get it back into 2wheel. also the service 4wheel drive light is almost always on. is this an accutator problem, vacum problem, or something more serious?

 

[DarkTahoe00]

If I was you I'd try to eliminate the first two by inspecting them. From what I've read that the switches are to go bad as well.