2002 GMC Sonoma Owner's Manual - Page 280

Hazard Warning Flashers The hazard warning flasher button is located on the top of the steering column. Your hazard warning flashers work no matter what position your key is in, and even if the key isn't in. Press the button to make the front and rear turn signal lamps flash on and off. Press the button again to turn the flashers off. 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. When the hazard warning flashers are on, your turn signals won't work. The flashers will stop if you step on the brake. 5-2