Service 4wd , Encoder Motor?

[casey38boost]

I recently picked up a 02 silverado 1500 4x4 4.8L v8 engine.

 

"Service 4wd" light comes on at startup and the push button 4x4 has no lights lit up.

 

I tried another push button unit but still nothing lights up.

 

I tried searching for this problem and some people are saying encoder motor or encoder sensor?

 

is it possible to tell what one it might be?

 

I guess I will try toget my body mondule codes read.

 

any help appreciated.