2008 gmc sierra 1500 service air bag light is on
Then get it serviced.
I had that problem on my 04. Check the airbag fuses, push on the plugs that plug into the airbag sensors behind the bumper. My fuse blew a couple of times. I wiggled the large wire loom behind the parking brake pedal and it stopped blowing the fuse.
Have someone connect a scanner that can read Air Bag codes.