GM Service Manual Online
For 1990-2009 cars only

The hazard warning flashers are controlled by the lever located to the right of the steering column.

(Hazard Warning Flasher): Move the lever up to make the front and rear turn signal lamps flash on and off. This warns others that you are having trouble. Move the lever down again to turn the flashers off.

When the hazard warning flashers are on, the turn signals will not work. The hazard warning flashers will not flash if the brakes are applied.