GMC Sierra Denali 2006, Owner'S Manual, Page: 215 / 438

Fixed Mast Antenna
The fixed mast antenna can withstand most car washes
without being damaged. If the mast should ever
become slightly bent, straighten it out by hand. If the
mast is badly bent, replace it.
Check occasionally to make sure the mast is still
tightened to the cowl. If tightening is required, tighten by
hand, then with a wrench one quarter turn.
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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