GMC 2006 Sierra - Manual (Page 249)

Notice: The chime signals related to safety belts,
parking brake, and other functions of your vehicle
operate through the GM radio/entertainment system.
If that equipment is replaced or additional equipment
is added to your vehicle, the chimes may not work.
Make sure that replacement or additional equipment
is compatible with your vehicle before installing it.
See Accessories and Modifications on page 5-4.
Your vehicle may have a feature called Retained
Accessory Power (RAP). With RAP, the audio system
can be played even after the ignition is turned off. See
Retained Accessory Power (RAP) on page 2-23 for more
information.
Setting the Time for Radios without
Radio Data Systems (RDS)
Press and hold HR until the correct hour appears on the
display. Press and hold MIN until the correct minute
appears on the display. There is an initial two-second
delay before the clock goes into time-set mode.
Display the time with the ignition off, by pressing RCL,
HR, or MIN.
Setting the Time for Radios with
Radio Data Systems (RDS)
The radio may have a button marked with an H or HR to
represent hours and an M or MN to represent minutes.
Press and hold the hour button until the correct hour
appears on the display. Press and hold the minute
button until the correct minute appears on the display.
The time can be set with the ignition on or off.
To synchronize the time with an FM station broadcasting
Radio Data System (RDS) information, press and hold
the hour and minute buttons at the same time until RDS
TIME appears on the display. To accept this time, press
and hold the hour and minute buttons, at the same time,
for another two seconds. If the time is not available from
the station, NO UPDAT will appear on the display.
RDS time is broadcast once a minute. After tuning to an
RDS broadcast station, it may take a few minutes for
the time to update.
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