2003 GMC Sonoma Owner's Manual - Page 14

Head Restraints Sitting in a reclined position when your vehicle is in motion canbe dangerous. Even if you buckle up, your safety belts can't do their job when you're reclined like this. The shoulder belt can't do its job because it won't be against your body. Instead, it will be in front of you. In a crash you could go intoit, receiving neck or other injuries. The lap belt can't do its job either. In a crash the belt could go up over your abdomen. The belt forces wouldbe there, not at your pelvic bones. This could cause serious internal injuries. For proper protection when the vehicle is in motion, have the seatback upright. Then sit well back in the seat and wear your safety belt properly. ~ Head restraints are fixed on some models and adjustable on others. Slide an adjustable head restraint up or down so that the top of the restraint is closest to the top of your head. This position reduces the chance of a neck injury in a crash. 1-7