GMC 2007 Envoy - Manual (Page 170)

Hazard Warning Flashers
The hazard warning flashers warn others.
They also let police know you have a problem.
Your front and rear turn signal lamps will flash on
and off.
The hazard warning
flasher button is located
on top of the steering
column.
The hazard warning flashers work no matter what
ignition position the key is in, and even if the
key is not in the ignition.
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.
When the hazard warning flashers are on, your
turn signals will not work.
Other Warning Devices
If you carry reflective triangles, you can set them up
at the side of the road about 300 feet (100 m)
behind your vehicle.
Horn
To sound the horn, press the horn symbols on the
steering wheel pad.
170