Horn
Pressa 
on the steering wheel pad
to sound the horn.
See also:
Cellular and GPS Antennas
Avoid placing items over or near the antenna to prevent blocking cellular and
GPS signal reception. Cellular reception is required for OnStar to send remote signals
to the vehicle. ...
Malfunction Indicator Lamp
A computer system called OBD II (On-Board Diagnostics-Second Generation) monitors
the operation of the vehicle to ensure emissions are at acceptable levels, to produce
a cleaner environment. This ...
Maintenance Replacement Parts
Replacement parts identified below by name, part number, or specification can
be obtained from your dealer.
If your vehicle has a diesel engine, see the Duramax diesel supplement for more
informa ...