light GMC SONOMA 1999 Service Manual

3-4
HEATER: This setting directs most of the
warmed air through the heater floor outlets and some air
through the windshield defroster outlets.
BLEND: Airflow is divided equally between the
heater floor outlet and the windshield defroster outlets.
DEFROST: This setting directs most air through
the windshield defroster outlets and some through the
heater outlets.
Air Conditioning (If Equipped)
On hot days, open the windows long enough to let hot
inside air escape. This reduces the time it takes for your
vehicle to cool down. Then keep your windows closed
for the air conditioner to work its best.
For quick cool
-down on very hot days, use MAX A/C
with the temperature knob turned counterclockwise.
This setting should be used to keep odors and/or dust
from entering the vehicle. For normal cooling on
hot days, use A/C with the temperature knob
turned counterclockwise.On cool but sunny days, use BI
-LEVEL A/C to deliver
warm air to the floor and cooler air to the instrument
panel outlets.
If you have the VORTEC 4300 V6 engine, when the
air conditioner is on, you may sometimes notice slight
changes in your vehicle's engine speed and power. This
is normal because the system is designed to cycle the
compressor on and off to keep the desired temperature.
Heating
The heater works best if you keep your windows closed
while using it. On cold days, use HEATER with the
temperature knob turned clockwise. BLEND is useful in
cool weather when you have fog or ice on the
windshield or side windows.
If you use the optional engine coolant heater before
starting your engine, your heating system will produce
warmer air faster to heat the passenger compartment in
cold weather. See ªEngine Coolant Heaterº in the Index.

3-7 AM-FM Stereo
Playing the Radio
VOLUME: This knob turns the system on and off and
controls the volume. To increase volume and turn the radio
on, turn the knob clockwise. Turn it counterclockwise to
decrease volume and turn the radio off.
RECALL: Display the time with the ignition off by
pressing the recall knob. When the radio is playing,
press this knob to recall the station frequency.Finding a Station
AM
-FM: Press the lower knob to switch between
AM and FM. The display shows your selection.
TUNE: Turn the lower knob to tune in radio stations.
SEEK: Press the right arrow to tune to the next higher
station and the left arrow to tune to the next lower
station and stay there.
SCAN: Select either AM, FM1 or FM2 mode and press
both SEEK buttons to listen to a few seconds of each
radio station. SCAN will light up on the display.
The radio will automatically SCAN to the next higher
station, play that station for a few seconds, then SCAN
to the next higher station. Press VOLUME or both
SEEK buttons to stop scanning.

3-12 AM-FM Stereo with Cassette Tape Player
and Automatic Tone Control (If Equipped)
Playing the Radio
PWR
-VOL: Press this knob to turn the system on and
off. To increase volume, turn the knob clockwise. Turn
it counterclockwise to decrease volume. The knob is
capable of being rotated continuously.
RECALL: Display the time with the ignition off by
pressing this button. When the radio is playing, press
this button to recall the station frequency.SCV: Your system has a feature called
Speed
-Compensated Volume (SCV). With SCV, your
audio system adjusts automatically to make up for road
and wind noise as you drive. Set the volume at the
desired level. Turn the control ring behind the upper
knob clockwise to adjust the SCV. Then, as you drive,
SCV automatically increases the volume, as necessary,
to overcome noise at any particular speed. The volume
level should always sound the same to you as you drive.
If you don't want to use SCV, turn the control all the
way down. Each notch on the control ring allows for
more volume compensation at faster vehicle speeds.
Finding a Station
AM
-FM: Press this button to switch between AM, FM1
and FM2. The display will show your selection.
TUNE: Press this knob lightly so it extends. Turn it to
choose radio stations. Push the knob back into its stored
position when you're not using it.
SEEK: Press the right arrow to tune to the next higher
station and the left arrow to tune to the next lower station
and stay there. The sound will mute while seeking.

3-13
SCAN: Press and hold SEEK for two seconds until
SCAN appears on the display. SCAN allows you to
listen to stations for a few seconds. The receiver will
continue to scan and momentarily stop at each station
until you press the button again. The sound will mute
while scanning.
PUSHBUTTONS: The six numbered pushbuttons let
you return to your favorite stations. You can set up to
18 stations (six AM, six FM1 and six FM2). Just:
1. Turn the radio on.
2. Press AM
-FM to select the band.
3. Tune in the desired station.
4. Press AUTO TONE to select the setting you prefer.
5. Press and hold one of the six pushbuttons. The sound
will mute. When it returns, release the button.
Whenever you press that numbered button, the
station you set will return and the tone you selected
will be automatically selected for that button.
6. Repeat the steps for each pushbutton.P.SCAN: The preset scan button lets you scan through
your favorite stations stored on your pushbuttons.
Select either the AM, FM1 or FM2 mode and then press
P. SCAN. It will scan through each station stored on your
pushbuttons and stop for a few seconds before continuing
to scan through all of the pushbuttons. Press P. SCAN
again or one of the pushbuttons to stop scanning to listen
to a specific preset station. P. SCAN will light up on the
display while in this mode. If one of the stations stored on
a pushbutton is too weak for the location you are in, the
radio display will show the channel number (P1
-P6) for
several seconds before advancing to the next preset station.
Setting the Tone
BASS: Press lightly on this knob to release it from its
stored position. Turn the knob clockwise to increase bass
and counterclockwise to decrease bass. When the BASS
control is rotated, the AUTO TONE display will go blank.
TREB: Press lightly on this knob to release it from its
stored position. Turn the knob clockwise to increase
treble and counterclockwise to decrease treble. When
the TREB control is rotated, the AUTO TONE display
will go blank. If a station is weak or noisy, you may
want to decrease the treble.
Push these knobs back into their stored positions when
you're not using them.

3-14
AUTO TONE: Press this button to select among the
six preset equalization settings and tailor the sound to the
music or voice being heard. Each time you press the
button, the selection will switch to one of the preset
settings of CLASSIC, NEWS, ROCK, POP, C/W
(Country/Western) or JAZZ. To return to the manual
mode, press and release this button until the AUTO TONE
display goes blank. This will return the tone adjustment to
the BASS and TREB controls. If a BASS or TREB
control is rotated, the AUTO TONE display will go blank.
Use PUSHBUTTONS to program AUTO TONE.
Adjusting the Speakers
BAL: Press lightly on this knob to release it from its
stored position. Turn the control clockwise to adjust
sound to the right speakers and counterclockwise to
adjust sound to the left speakers. The middle position
balances the sound between the speakers.
FADE: Press lightly on this knob to release it from its
stored position. Turn the control clockwise to adjust the
sound to the front speakers and counterclockwise for the
rear speakers. The middle position balances the sound
between the speakers.
Push these knobs back into their stored positions when
you're not using them.Playing a Cassette Tape
Your tape player is built to work best with tapes that are
up to 30 to 45 minutes long on each side. Tapes longer
than that are so thin they may not work well in this player.
To load a cassette tape with the ignition off, press EJECT
or RECALL. Then, insert the cassette tape. If the ignition
is on but the radio is off, the tape will begin playing.
Once the tape is playing, use the VOL, AUTO TONE,
BAL, FADE, BASS and TREB controls just as you do
for the radio. The tape symbol and a direction arrow will
be on the display whenever a tape is being played.
Anytime a tape is inserted, the top side is selected for
play first.
The player automatically senses if the cassette tape is
metal or CrO
2 and adjusts for best playback sound.
PREV (1): Press the PREV button or the SEEK left
arrow to search for the previous selection. A minimum
three
-second blank gap is required for the player to stop
at the beginning of the selection. The tape direction
arrow will blink during the SEEK operation.
PROG (2): Press this button to switch from one side of
the tape to the other.

3-15
NEXT (3): Press the NEXT button or the SEEK right
arrow to search for the next selection. A minimum
three
-second blank gap is required for the player to stop
at the beginning of the selection. The tape direction
arrow will blink during the SEEK operation. The sound
will mute while searching for the next selection.
REV (4): Press this button to rapidly reverse the tape to
the beginning of the cassette or until you press REV
again. The radio will play the last selected station while
reversing the tape. The tape direction arrow will blink
during the reverse operation.

(5): Press this button to reduce cassette tape noise.
The double
-D symbol will appear on the display while
the player is in this mode.
Dolby Noise Reduction is manufactured under a
license from Dolby Laboratories Licensing Corporation.
Dolby and the double
-D symbol are trademarks of
Dolby Laboratories Licensing Corporation.
FWD (6): Press this button to rapidly forward the tape
to the end of the cassette or until you press FWD again.
The radio will play the last selected station while
forwarding the tape. The tape direction arrow will blink
during the forward operation.AM
-FM: Press this button to switch from a tape
to the radio.
TAPE AUX: Press this button to return to the tape
player when playing the radio. The lighted arrow will
appear and show the direction of play when a tape is in
the active mode.
EJECT: Press this button to remove the tape. The radio
will now play. EJECT can be used with either the ignition
or radio off. To load a cassette tape with the ignition or
radio off, press EJECT before loading the cassette.
CLN: If this message appears on the display, the
cassette tape player needs to be cleaned. It will still play
tapes, but you should clean it as soon as possible to
prevent damage to the tapes and player. See ªCare of
Your Cassette Tape Playerº in the Index. After you clean
the player, press and hold EJECT for five seconds to
reset the CLN indicator. The radio will display
--- to
show the indicator was reset.

3-17
SCV: Your system has a feature called
Speed
-Compensated Volume (SCV). With SCV, your
audio system adjusts automatically to make up for road
and wind noise as you drive. Set the volume at the
desired level. Turn the control ring behind the upper
knob clockwise to adjust the SCV. Then, as you drive,
SCV automatically increases the volume, as necessary,
to overcome noise at any particular speed. The volume
level should always sound the same to you as you drive.
If you don't want to use SCV, turn the control all the
way down. Each notch on the control ring allows for
more volume compensation at faster vehicle speeds.
Finding a Station
AM
-FM: Press this button to switch between AM, FM1
and FM2. The display will show your selection.
TUNE: Press this knob lightly so it extends. Turn it to
choose radio stations. Push the knob back into its stored
position when you're not using it.
SEEK: Press the right arrow to tune to the next higher
station and the left arrow to tune to the next lower station
and stay there. The sound will mute while seeking.SCAN: Press and hold SEEK for two seconds until
SCAN appears on the display. SCAN allows you to
listen to stations for a few seconds. The receiver will
continue to scan and momentarily stop at each station
until you press the button again. The sound will mute
while scanning.
PUSHBUTTONS: The six numbered pushbuttons let
you return to your favorite stations. You can set up to
18 stations (six AM, six FM1 and six FM2). Just:
1. Turn the radio on.
2. Press AM
-FM to select the band.
3. Tune in the desired station.
4. Press AUTO TONE to select the setting you prefer.
5. Press and hold one of the six pushbuttons. The sound
will mute. When it returns, release the button.
Whenever you press that numbered button, the
station you set will return and the tone you selected
will be automatically selected for that button.
6. Repeat the steps for each pushbutton.

3-18
P.SCAN: The preset scan button lets you scan through
your favorite stations stored on your pushbuttons.
Select either the AM, FM1 or FM2 mode and then press
P.SCAN. It will scan through each station stored on your
pushbuttons and stop for a few seconds before continuing
to scan through all of the pushbuttons. Press P.SCAN
again or one of the pushbuttons to stop scanning to listen
to a specific stored station. P.SCAN will light up on the
display while in this mode. If one of the stations stored on
a pushbutton is too weak for the location you are in, the
radio display will show the channel number (P1
-P6) for
several seconds before advancing to the next preset station.
Setting the Tone
BASS: Press lightly on this knob to release it from its
stored position. Turn the knob clockwise to increase bass
and counterclockwise to decrease bass. When the BASS
control is rotated, the AUTO TONE display will go blank.
TREB: Press lightly on this knob to release it from its
stored position. Turn the knob clockwise to increase
treble and counterclockwise to decrease treble. When
the TREB control is rotated, the AUTO TONE display
will go blank. If a station is weak or noisy, you may
want to decrease the treble.
Push these knobs back into their stored positions when
you're not using them.AUTO TONE: Press this button to select among the
six preset equalization settings and tailor the sound to the
music or voice being heard. Each time you press the
button, the selection will switch to one of the preset
settings of CLASSIC, NEWS, ROCK, POP, C/W
(Country/Western) or JAZZ. To return to the manual
mode, press and release this button until the AUTO TONE
display goes blank. This will return the tone adjustment to
the BASS and TREB controls. If a BASS or TREB
control is rotated, the AUTO TONE display will go blank.
Use PUSHBUTTONS to program AUTO TONE.
Adjusting the Speakers
BAL: Press lightly on this knob to release it from its
stored position. Turn the control clockwise to adjust
sound to the right speakers and counterclockwise to
adjust sound to the left speakers. The middle position
balances the sound between the speakers.
FADE: Press lightly on this knob to release it from its
stored position. Turn the control clockwise to adjust the
sound to the front speakers and counterclockwise for the
rear speakers. The middle position balances the sound
between the speakers.
Push these knobs back into their stored positions when
you're not using them.

3-20
AM-FM: While in the CD mode, press this button to
stop playing the CD and play the radio. The CD symbol
will still display but the word CD will be replaced with
either AM, FM1 or FM2. (If the radio is turned off, the
disc stays in the player and will resume playing at the
point where it stopped.)
CD AUX: To switch between the player and the radio
when a disc is playing, press the AM
-FM button. To
return to the player, press CD AUX. When a disc is
playing, the letters CD and the CD symbol will appear
on the display. (If the radio is turned off, the disc stays
in the player and will resume playing at the point where
it stopped.)
EJECT: Press this button to eject the disc from the
player and play the radio. When the same or a new disc
is inserted, the disc will start playing on track one. If a
compact disc is left sitting in the opening for more than
a few seconds, the player will pull the CD back in. The
radio will continue playing. When the ignition is off,
press this button to load a CD.
Remote Cassette Tape Player (If Equipped)
If you have an AM-FM Stereo Audio Compact Disc
Automatic Tone Control System that includes a remote
cassette player, the cassette player is located in the
center of the instrument panel.
Your tape player is built to work best with tapes that are
up to 30 to 45 minutes long on each side. Tapes longer
than that are so thin they may not work well in this player.
To load a cassette tape with the ignition off, first press
EJECT on the remote player. Then, insert the cassette tape.
The tape will play if the ignition is on but the radio is off.
Once the tape is playing, use the control knobs for VOL,
AUTO TONE, BAL, FADE, BASS and TREB just as
you do for the radio. A lighted tape symbol shows when
a cassette tape is in the player. A lighted arrow will
also appear and show the direction of play when a
tape is active.

3-21
The player automatically senses if the cassette tape is
metal or CrO
2 and adjusts for best playback sound.
Anytime a cassette tape is inserted, the top side is
selected for play first.
PREV (1): Press PREV or the SEEK left arrow (in the
opposite direction that the lighted tape direction arrow
points) to search for the previous selection. A minimum
three
-second blank gap is needed for the player to stop
at the beginning of the selection. The tape direction
arrow will blink during the SEEK operation and the
sound is muted in this mode.
NEXT (3): Press NEXT or the SEEK right arrow (in the
direction that the lighted tape direction arrow points) to
search for the next selection. The tape direction arrow
will blink during SEEK operation and the sound is
muted in this mode.
REV (4): Press this button to rapidly reverse the tape.
The tape will rapidly reverse to the beginning of the
cassette reel or until you press REV again. The radio
plays the last selected station during REV.(5): Press this pushbutton to turn Dolby on and off. Dolby
is active when a tape is inserted in the remote cassette. The
double
-D symbol will appear on the display.
Dolby Noise Reduction is manufactured under a license
from Dolby Laboratories Licensing Corporation. Dolby
and the double
-D symbol are trademarks of Dolby
Laboratories Licensing Corporation.
FWD (6): Press this button to rapidly advance the tape.
The tape will rapidly advance to the end of the cassette
reel or until you press FWD again. The radio plays the
last selected station during FWD.
PROG: Press this button on the remote player to go
from one side of the tape to the other.
TAPE: Press the AM
-FM button to switch from the
player and the radio when a tape is playing. To return to
the tape player, press CD AUX. The lighted arrow will
appear next to the symbol and show the direction of play
when a tape is active.
EJECT: Press this button on the remote player to
remove the tape. EJECT can be used with either the
ignition or radio off. Also, you must press EJECT before
loading a cassette with the radio off to allow loading.