GMC SIERRA DENALI 2002 Manual page 173

Rear Seat Audio Controls
The following functions are controlled by the RSA
system buttons:
PWR (Power): Press this button to turn the rear seat
audio system on or off. The rear speakers will be muted
when the power is turned on. You may operate the rear
seat audio functions even when the primary radio power
is off.
3-14
VOL (Volume): Press this knob lightly so it extends.
Turn the knob clockwise to increase volume and
counterclockwise to decrease volume. Push the knob
back into its stored position when you're not using it.
The upper knob controls the upper headphone and the
lower knob controls the lower headphone.
AM FM: Press this button to switch between AM, FM1
and FM2. If the front passengers are already listening to
AM FM, the RSA controller will not switch between the
bands and cannot change the frequency.
Press AM FM to return to listening to the radio when a
cassette tape or CD is playing. The inactive tape or CD
will remain safely inside the radio for future listening.
SEEK : While listening to AM, FM1 or FM2,
press the up arrow to tune to the next station and stay
there. Press the down arrow to tune to the previous
station and stay there. The sound will mute while
seeking. If the front radio is in use, you cannot seek
through different stations.