2005 GMC Canyon Owner's Manual - Page 34

The safety belt locks if there is a sudden stop or a crash. The safety belt also locks if you pull the belt very quickly out of the retractor. {CAUTION: You can be seriously hurt if your shoulder belt is too loose. In a crash, you would move forward too much, which could increase injury. The shoulder belt should fit against your body. To unlatch the belt, just push the button on the buckle. 1-28