GMC 2006 Sierra - Manual (Page 311)

XM™ Satellite Radio Antenna
System
The XM™ Satellite Radio antenna is located on the roof
of your vehicle. Keep this antenna clear of snow and ice
build up for clear radio reception.
If your vehicle has a sunroof, the performance of the
XM™ system may be affected if the sunroof is open.
Loading items onto the roof of your vehicle can interfere
with the performance of the XM™ system. Make sure
the XM™ Satellite Radio antenna is not obstructed.
Chime Level Adjustment
The radio is used to adjust the vehicle’s chime level.
To change the volume level of the chime, press and hold
pushbutton 6 with the ignition on and the radio power off.
The volume level will change from the normal level to
loud, and LOUD will appear on the radio display. To
change back to the default or normal setting, press and
hold pushbutton 6 again. The volume level will change
from the loud level to normal, and NORMAL will appear
on the radio display. Each time the chime volume is
changed, three chimes will sound as an example of the
new volume selected. Removing the radio and not
replacing it with a factory radio or chime module will
disable vehicle chimes.
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