This is my first post, hope you can help! I drive a 04 Z71 1500 with 200k. Last week I put the truck in 4HI and jacked up the rear and changed my rear U-joints. When I was finished and backed the truck down my driveway, put it in neutral and then tried putting the truck in 2WD and it went to Auto 4Wheel. It will not get out of that mode now. The orange light just flashes for a moment on whatever button I push, then returns up top to Auto. Across the odometer, it reads Service 4 Wheel......but not all the time. Sometimes when I am driving and sometimes when I first start the engine, and like this morning, both when I started and all the way to work.

 

I have a 04 GMC Z71 and when I first bought it all the selection lights came on and wouldn't go off. I took it to the dealer and they fixed it. They said they reloaded the software. Maybe that's your problem too.

 

I have been fighting the same problem with my 02 1500 Z71... I have replaced the push button on the dash the front actuator and now it wont go into 4wd... But the way that i got my truck out of auto 4 is i shut the truck off put it in N and pressed the 2HI and refired it... Then it was back in 2HI but you also might have to disconnect the battery for about ten mins then try what i just said... It should work... But im getting ready to put a new encoder motor in the Tcase to see if that works and if it dont she is going to the dealership... Hope this helps ya bub good luck...