1996 GMC Yukon Owner's Manual - Page 217

Section 5 Problems On The Road Here you'll find what to do about some problems that can occur on the road. But they won't flash if you're braking. Press the button at the top of the steering column all the way down to make your front and rear turn signal lamps flash on and off. Hazard Warning Flashers Your hazard warning flashers work no matter what position your key is in, and even if the key isn't in. Your hazard warning flashers let you warn others. They also let police know you have a problem. Your front and rear turn signal lamps will flash on and off. To turn off the flashers, push the button until the first click and release. When the hazard warning flashers are on, your turn signals won't work. 5-1