Buick RIVIERA 1993 Manual page 187

I
Press the button in to make your front and rear turn
signal lights flash on and off.
Your hazard warning flashers work no matter what
position your key is in, and even if the key isn't in.
To turn off the flashers, pull out on the collar. When the
hazard warning flashers are on, your turn signals won't
work.
Other Warning Devices
If you carry reflective triangles, you can set one up at
the side of the road about 300 feet (100 m) behind your
vehicle.
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