2004 Gmc Sierra 4wd issue?

[nick]

The other day I started my truck 04 gmc sierra 4wd and when I did where the digital mileage is it said service 4wd and it wouldn't let me put it in 4wd at all.Today I started it up and it dint say service 4wd and I can now put it in 4wd.Just wondering if any1 had any ideas as to what is up and if I should get worried and have it serviced?

 

[Jaimeot]

it has to be an electric falure but u can put a scanner in the computer plug that is supose to be under the dash at the drivers seat connected and write the code then look in the internet for the meanning by the scanner model

 

[ray p]

if this message comes on again,take a look at the left frame under cab mount there is a ground there make sure its clean and no wires are loose ,wouldn,t hurt to remove it and clean the connection or surface