GMC TopKick 2007 Owner's Manual page 188

Setting the Tone (Bass/Treble)
AUDIO: To adjust bass and treble, press and
release AUDIO until BAS (bass) or TRE (treble)
appears on the display. Then press and hold
the up or the down arrow to increase or to
decrease. If a station is weak or has static,
decrease the treble.
To adjust bass or treble to the middle position,
select BAS or TRE. Then press and hold AUDIO
for more than two seconds until you hear a
beep. B and a zero or T and a zero appears on
the display.
To adjust both tone controls and both speaker
controls to the middle position, end out of audio by
waiting for the display to change to the clock
display. Then press and hold AUDIO for more than
two seconds until you hear a beep. CEN (center)
appears on the display.
188
Adjusting the Speakers (Balance/Fade)
AUDIO: To adjust the balance between the
right and the left speakers, press and release
AUDIO until BAL (balance) appears on the display.
Then press and hold the up or the down arrow
to move the sound toward the right or the
left speakers.
To adjust the fade between the front and the
rear speakers, press and release AUDIO until
FAD (fade) appears on the display. Then press
and hold the up or the down arrow to move
the sound toward the front or the rear speakers.
To adjust balance or fade to the middle position,
select BAL or FAD. Then press and hold AUDIO for
more than two seconds until you hear a beep.
L (balance) and a zero or F and a zero appears on
the display.
To adjust both tone controls and both speaker
controls to the middle position, end out of audio by
waiting for the display to change to the time display.
Then press and hold AUDIO for more than
two seconds until you hear a beep. CEN (center)
appears on the display.
Fade may not be available if the vehicle is a regular
cab model.