Four wheel drive problems

I have a 2009 silverado 1500 z71 5.3 V8. The truck will not shift into 4x4. When I try to go into 4hi the light in the twist knob just blinks and then says service 4 wheel drive. When I go into 4lo the truck goes into lo gear like it is supposed to do, but the wheels won't engage. The 4x4 light never shows up on my dash like it has engaged. Can anyone help me?

I have a 2009 silverado 1500 z71 5.3 V8. The truck will not shift into 4x4. When I try to go into 4hi the light in the twist knob just blinks and then says service 4 wheel drive. When I go into 4lo the truck goes into lo gear like it is supposed to do, but the wheels won't engage. The 4x4 light never shows up on my dash like it has engaged. Can anyone help me?

1st thing you need to do is get the Transfer Case Control Module (tccm) codes read. My first guess would be an encoder sensor problem. Without a code though, it's just a guess.

I have a 2009 silverado 1500 z71 5.3 V8. The truck will not shift into 4x4. When I try to go into 4hi the light in the twist knob just blinks and then says service 4 wheel drive. When I go into 4lo the truck goes into lo gear like it is supposed to do, but the wheels won't engage. The 4x4 light never shows up on my dash like it has engaged. Can anyone help me?

as was mentioned having a GM drive train code reader and having the code[s] will narrow down whats not working but may not for sure say what is broken... wiring defects are big on these if a person was messing with them or the fuse box area including spark plug replacing as the wire harness is with very small easy to break wires. when you try to go to 4wd from 2wd and it just blinks this is usually a encoder transfer case motor/or wiring.. when did you last service the transfer case ? what is the fluid color ? if black then this may very well mean a re-build.