Chevrolet 2003 Silverado Owner's Manual page 36

3. Be sure that the belt is not twisted and it lies flat.
The guide must be on top of the belt.
1-30
4. Buckle, position and release the safety belt as
described in Rear Seat Passengers on page 1-26 .
Make sure that the shoulder belt crosses the
shoulder.
To remove and store the comfort guides, squeeze the
belt edges together so that you can take them out of the
guides. Slide the guide onto the storage clip.