GM Service Manual Online
For 1990-2009 cars only

System Description

The following audio systems are available:

Delco® AM/FM Stereo


Object Number: 623241  Size: SH
    • Radio AM/FM stereo
    • Seek
    • Clock
    • Electronically tuned receiver (ETR)

Delco® AM/FM Stereo With A Cassette Player


Object Number: 623239  Size: SH
    • Radio AM/FM stereo
    • Seek
    • Preset tone settings for sound quality
    • Clock
    • Electronically tuned receiver (ETR)
    • Auto Reverse music search cassette

Delco® AM/FM Stereo With A Compact Disc Player


Object Number: 623238  Size: SH
    • Radio AM/FM stereo
    • Seek
    • Preset tone settings for sound quality
    • Clock
    • Electronically tuned receiver (ETR)
    • Compact disc player

The audio system consists of the following components:

    • The radio
    • Four speakers
    • The antenna

The ignition switch must be in the ACC or ON positions in order to operate any of the sound systems. The front speakers are located on the lower part of the front doors. The two rear speakers are located below the rear window to seat back trim panel.

Important: All GM factory-equipped audio systems have ungrounded speakers. Installing after-market tape players, citizen band radios or other units that use the factory speakers may damage the audio system or impair the operation of the after-market unit.

FM Radio Reception

The FM tuner operates on a band from 87.7 MHz to 107.9 MHz. Optimum FM radio reception range is usually limited to a maximum of 16 to 64 kilometers (10 to 40 miles). The range depends upon the following conditions:

    • The terrain
    • The atmospheric conditions
    • The station power
    • The antenna height
    • The distance from the transmitter.

Signal flutter or noise may result from the following:

    • Tall buildings
    • Hills
    • Other objects

You may eliminate this problem by tuning to a stronger station.

AM Radio Reception

The AM tuner operates on a band from 530 kHz to 1710 kHz. The range of most AM stations is greater than FM, especially at night. The longer range may cause stations to interfere with each other. AM reception is also subject to noise interference from storms, power lines, etc. Reduce the treble in order to help reduce the noise.

AM/FM Stereo System Operation


Object Number: 623241  Size: SH

Radio Display Illumination

Turning the headlamps or the park lamps on will give the IP lamp dimmer control of the illumination of the display. The dimmer is located on the instrument panel to the left of the steering wheel. If the headlamps or the park lamps are off, the intensity of the display's illumination is 100 percent. The display is not adjustable.

PWR/ VOL

The ignition switch must be in the ACC position or in the ON position in order to operate the radio. If the ignition is in the OFF position, press the RCL/TUNE knob in order to display the time for 5 seconds. If the ignition switch is in the ACC position or in the ON position, and if the radio is off, the time will display. In this instance, all controls except those controls that are required to set the clock will deactivate. Press the PWR/ VOL knob in order to turn the radio on. Turn the knob clockwise in order to increase the sound. In order to decrease the sound, turn the knob counterclockwise. Press the PWR/ VOL knob again in order to turn the radio off.

Recall

Press the RCL/TUNE knob with the radio on in order to toggle the display between the following:

  1. The clock
  2. The band
  3. The radio frequency

Pressing the knob once will change the display from the clock to the band mode. Pressing the knob a second time within approximately 2 seconds will change the display from the band to the radio frequency mode. If the knob is not pressed a second time, the display will change from the band to the radio frequency within 2 seconds automatically. After approximately 5 seconds, the display will return to the clock.

AM/FM

Press this button in order to move between the AM band and the FM band. AM or FM will appear on the display, depending on the band that you select. The radio will automatically go to the frequency that was playing when the band was last used.

SEEK

Press the right end of the SEEK button to automatically tune to the next higher station within range. Press the left end of the SEEK button to automatically tune to the next lower station within range. Upon reaching the end of the band, the seek function will continue in the same direction at the opposite end of the band.

TUNE

Turn the RCL/TUNE knob clockwise in order to manually tune the radio frequency forward. Turn the RCL/TUNE knob counterclockwise in order to manually tune the radio frequency backward. On the AM band, the frequency advances in increments of 10 kHz in either direction. On the FM band, the frequency advances in increments of 0.2 MHz in either direction. Upon reaching the end of the band, the tune function will continue in the same direction at the opposite end of the band.

Radio Frequency Preset Buttons

The radio has 6 preset buttons. The buttons are numbered 1 through 6. You can preset 6 stations on the AM band and 6 stations on the FM band. In order to set a station preset button, perform the following steps:

  1. Select the AM band or the FM band.
  2. Tune the radio to the desired station.
  3. Press and hold the desired preset button. Press and hold the button for approximately three seconds.
  4. When a beep sounds, release the button.
  5. The button is now set to the desired station. The radio will now automatically tune the selected station when the button is pressed.

If power to the radio unit is interrupted, the memory of the preset buttons is lost. Reset the preset buttons if the buttons' memory is lost.

Setting the Tone

In order to adjust the bass, press the audio button until BAS appears on the display. The radio is now in the bass mode. Press the down arrow in order to decrease the bass. Press the up arrow in order to increase the bass. In order to adjust the treble, press the audio button until TRE appears on the display. The radio is now in the treble mode. Press the down arrow in order to decrease the treble. Press the up arrow in order to increase the treble. After either adjustment, the radio display will return to the clock after approximately 5 seconds.

Adjusting the Speaker Balance

In order to adjust the balance, press the audio button until BAL appears on the display. The radio is now in the balance mode. Press the down arrow in order to move the sound to the left speakers. Press the up arrow in order to move the sound to the right speakers. In order to adjust the fade mode, press the audio button until FAD appears on the display. The radio is now in the fade mode. Press the down arrow in order to move the sound to the rear speakers. Press the up arrow in order to move the sound to the front speakers. After either adjustment, the radio display will return to the clock after approximately 5 seconds.

Clock Operation

The clock function of this radio does not have a memory function. If power to the radio is interrupted, you will have to reset the clock.

Setting the Clock

In order to set the clock, the ignition switch must be in the ACC position or in the ON position. The radio may be turned on or off.

In order to set the hour, perform the following steps:

  1. Press and hold the down arrow button (HR). After approximately 5 seconds a beep will sound, and the hour will advance.
  2. Release the button when the correct hour appears.

In order to set the minutes, perform the following steps:

  1. Press and hold the up arrow button (MIN). After approximately 5 seconds a beep will sound, and the minutes will advance.
  2. Release the button when the correct minute appears.

AM/FM Stereo With A Cassette Player System Operation


Object Number: 623239  Size: SH

Radio Display Illumination

Turning the headlamps or the park lamps on will give the IP lamp dimmer control of the illumination of the display. The dimmer is located on the instrument panel to the left of the steering wheel. When the headlamps or the park lamps are off, the intensity of the display's illumination is 100 percent. The display is not adjustable.

PWR/ VOL

The ignition switch must be in the ACC position or in the ON position in order to operate the radio. If the ignition is in the OFF position, press the RCL/TUNE knob in order to display the time for 5 seconds. When the ignition switch is in the ACC position or in the ON position and the radio is off, the time will display. In this instance, all controls, except for the eject button and for the controls that are required to set the clock, will deactivate. The eject button has an up arrow and a line at the bottom. Press the PWR/ VOL knob in order to turn the radio on. Turn the knob clockwise in order to increase the sound. In order to decrease the sound, turn the knob counterclockwise. Press the PWR/ VOL knob again in order to turn the radio off.

Recall

Press the RCL/TUNE knob with the radio on in order to toggle the display between the following:

  1. The clock
  2. The band
  3. The radio frequency

Pressing the knob once will change the display from the clock to the band mode. Pressing the knob a second time within approximately 2 seconds will change the display from the band to the radio frequency mode. If the knob is not pressed a second time, the display will change from the band to the radio frequency within 2 seconds automatically. After approximately 5 seconds, the display will return to the clock.

AM/FM

Press this button in order to move between the AM band and the FM band. AM or FM will appear on the display, depending on the band which is active. The radio will automatically go to the frequency that was playing when the band was last being used.

SEEK

Press the right end of the SEEK button to automatically tune to the next higher station within range. Press the left end of the SEEK button to automatically tune to the next lower station within range. Upon reaching the end of the band, the seek function will continue in the same direction at the opposite end of the band.

TUNE

Turn the RCL/TUNE knob clockwise in order to manually tune the radio frequency forward. Turn the RCL/TUNE knob counterclockwise in order to manually tune the radio frequency backward. On the AM band, the frequency advances in increments of 10 kHz in either direction. On the FM band, the frequency advances in increments of 0.2 MHz in either direction. Upon reaching the end of the band, the tune function will continue in the same direction at the opposite end of the band.

Radio Frequency Preset Buttons

The radio has 6 preset buttons. The buttons are numbered 1 through 6. The buttons permit you to preset 6 stations on the AM band and 12 stations on the FM band. In order to set a station preset button:

  1. Select the AM band or the FM band.
  2. Tune the radio to the desired station.
  3. Press and hold the desired preset button. Press and hold the button for approximately three seconds.
  4. When a beep sounds, release the button.
  5. The button is now set to the desired station. The radio will now automatically tune the selected station when the button is pressed.

If power to the radio unit is interrupted, the memory of the preset buttons will be lost. Reset the preset buttons if the buttons' memory is lost.

The preset buttons control different functions when a tape is playing. Refer to Cassette Player Operation for details on these other functions.

Setting the Tone

In order to adjust the bass, press the audio button until BAS appears on the display. The radio is now in the bass mode. Press the down arrow in order to decrease the bass. Press the up arrow in order to increase the bass. In order to adjust the treble, press the audio button until TRE appears on the display. The radio is now in the treble mode. Press the down arrow in order to decrease the treble. Press the up arrow in order to increase the treble. After either adjustment, the radio display will return to the clock after approximately 5 seconds.

Adjusting the Speaker Balance

In order to adjust the balance, press the audio button until BAL appears on the display. The radio is now in the balance mode. Press the down arrow in order to move the sound to the left speakers. Press the up arrow in order to move the sound to the right speakers. In order to adjust the fade mode, press the audio button until FAD appears on the display. The radio is now in the fade mode. Press the down arrow in order to move the sound to the rear speakers. Press the up arrow in order to move the sound to the front speakers. After either adjustment, the radio display will return to the clock after approximately 5 seconds.

Clock Operation

The clock function of this radio does not have a memory function. If power to the radio is interrupted, you will have to reset the clock.

Setting the Clock

In order to set the clock, the ignition switch must be in the ACC position or in the ON position. The radio may be turned on or off.

In order to set the hour, perform the following steps:

  1. Press and hold the down arrow button (HR). After approximately 5 seconds a beep will sound, and the hour will advance.
  2. Release the button when the correct hour appears.

In order to set the minutes, perform the following steps:

  1. Press and hold the up arrow button (MIN). After approximately 5 seconds a beep will sound, and the minutes will advance.
  2. Release the button when the correct minute appears.
    • Turn the ignition switch to the ACC position or to the ON position.
    • Turn the radio on, or insert the tape.

The cassette player is designed to work best with tapes which are 60 to 90 minutes long. Longer tapes are thinner. Longer tapes may not function correctly in this unit. Do not use these tapes in order to diagnose problems in the cassette player.

Insert the cassette into the unit with the visible side of the tape to the right. The tape may not be seated squarely in the cassette player if the following conditions occur:

    • You hear no sound.
    • You hear garbled sound.

Cassette Player Operation

In order to operate the cassette player, perform the following steps:

In order to correct this problem, press the eject button in order to remove the tape. The eject button has an up arrow and a line at the bottom. Install the tape. If you insert a metal or a chrome cassette tape, MTL will appear on the display. If the tape begins to play, you may use the following controls in the same manner as with the radio:

    • Volume
    • Treble
    • Bass
    • Balance
    • Fade

The cassette radio has a feature in order to determine if a cassette tape is broken. If the take-up reel spins faster than a set threshold, the cassette player assumes that the tape is broken. The tape will eject. Perform the following steps in order to disable this feature:

  1. Turn the ignition on.
  2. Turn the radio off.
  3. Press and hold the TAPE button for 3 seconds.

The CAS icon will flash 5 times in order to indicate that this feature has been disabled. The Cut Tape Detection feature will remain disabled until you press the eject button.

AM/FM

If the cassette is playing, press the AM/FM band button in order to perform the following functions:

  1. Stop the tape.
  2. Retract the pinch rollers.
  3. Switch the radio to the receiver mode.

Fast Forward

Either of the following actions activate the fast forward function:

    • Press the arrows on the right end of the SEEK button.
    • Press the preset button 4 (FWD).

This fast-forwards the tape in the direction of play. Press one of the following buttons in order to return to the normal playing speed:

    • The right end of the SEEK button
    • The preset button 4 (FWD)
    • The TAPE button

Important

Press preset button 5 (SIDE) in order to change the tape side. This also stops the fast forward operation.

Rewind

Either of the following actions activate the rewind operation:

    • Press the arrows on the left end of the SEEK button.
    • Press the preset button 3 (REV).

This will rewind the tape opposite to the direction of play. Press one of the following buttons in order to return to the normal playing speed:

    • The left end of the SEEK button
    • The preset button 3 (REV)
    • The TAPE button

Important

Press preset button 5 (SIDE) in order to change the tape side. This also stops the rewind operation.

Next Selection

Press preset button 2 (NEXT) in order to activate the next selection function. This will cause the tape to move to the beginning of the next selection. Press preset button 2 (NEXT) or the TAPE button in order to return to the normal playing speed.

Important

Press preset button 5 (SIDE) in order to change the tape side. This stops the next selection operation.

Previous Selection

Press preset button 1 (PREV) in order to activate the previous selection function. This will cause the tape to move to the beginning of the current selection. For the correct operation of the previous selection function, the current selection must have been playing for more than 10 seconds. If the current selection has been playing for less than 10 seconds, then the tape will rewind to the beginning of the previous selection. Press preset button 1 (PREV) or the TAPE button in order to return to the normal playing speed.

Important

Press preset button 5 (SIDE) in order to change the tape side. This stops the previous selection function.

Changing Programs

Press preset button 5 (SIDE) in order to change to the other side of the tape. The display will show UP or DN depending on the side of the tape that the cassette player currently plays.

Eject

Press the eject button in order to remove the tape. The eject button has an up arrow and a line at the bottom. This also stops the tape. The unit will return to radio operation.

Tape

If you push the TAPE button, and a tape is loaded, and the radio is in the receiver mode, the following actions will occur:

  1. The receiver mode will cancel.
  2. The display will show CAS.
  3. The display will show the direction of play as UP or as DN.
  4. The tape will begin to play correctly.

If you push the TAPE button, the cassette player will change tape sides and cancel any of the following modes:

  1. REV
  2. FWD
  3. PREV
  4. NEXT

AM/FM Stereo With A CD Player System Operation


Object Number: 623238  Size: SH

Radio Display Illumination

Turning the headlamps or the park lamps on will give the IP lamp dimmer control of the illumination of the display. The dimmer is located on the instrument panel to the left of the steering wheel. If the headlamps or the parking lamps are off, the intensity of the display's illumination is 100 percent. The display is not adjustable.

PWR/ VOL

The ignition switch must be in the ACC position or in the ON position in order to operate the radio. If the ignition is in the OFF position, press the RCL/TUNE knob in order to display the time for 5 seconds. If the ignition switch is in the ACC position or in the ON position and the radio is turned off, the time will display. In this instance, all controls, except for the eject button and for the controls that are required to set the clock, will deactivate. The eject button has an up arrow and a line at the bottom. Press the PWR/ VOL knob in order to turn the radio on. Turn the knob clockwise in order to increase the sound. In order to decrease the sound, turn the knob counterclockwise. Press the PWR/ VOL knob again in order to turn the radio off.

Recall

Press the RCL/TUNE knob with the radio on in order to toggle the display between the following:

  1. The clock
  2. The band
  3. The radio frequency

Pressing the knob once will change the display from the clock to the band mode. Pressing the knob a second time within approximately 2 seconds will change the display from the band to the radio frequency mode. If the knob is not pressed a second time, the display will change from the band to the radio frequency within 2 seconds automatically. After approximately 5 seconds, the display will return to the clock.

AM/FM

Press this button in order to move between the AM band and the FM band. AM or FM will appear on the display, depending on the band that you select. The radio will automatically go to the frequency that played when that band was last used.

SEEK

Press the right end of the SEEK button to automatically tune to the next higher station within range. Press the left end of the SEEK button to automatically tune to the next lower station within range. Upon reaching the end of the band, the seek function will continue in the same direction at the opposite end of the band.

TUNE

Turn the RCL/TUNE knob clockwise in order to manually tune the radio frequency forward. Turn the RCL/TUNE knob counterclockwise in order to manually tune the radio frequency backward. On the AM band, the frequency advances in increments of 10 kHz in either direction. On the FM band, the frequency advances in increments of 0.2 MHz in either direction. Upon reaching the end of the band, the tune function will continue in the same direction at the opposite end of the band.

Radio Frequency Preset Buttons

The radio has six preset buttons. The buttons are numbered 1 through 6. The buttons permit you to preset 6 stations on the AM band and 12 stations on the FM band. In order to set a station preset button:

  1. Select the AM band or the FM band.
  2. Tune the radio to the desired station.
  3. Press and hold the desired preset button. Press and hold the button for approximately three seconds.
  4. When a beep sounds, release the button.
  5. The button is now set to the desired station. The radio will now automatically tune the selected station when the button is pressed.

If power to the radio unit is interrupted, the memory of the preset buttons will be lost. Reset the preset buttons if the buttons' memory is lost.

The preset buttons control different functions if a compact disc is playing. Refer to Compact Disc Player Operation for details on these other functions.

Setting the Tone

In order to adjust the bass, press the audio button until BAS appears on the display. The radio is now in the bass mode. Press the down arrow in order to decrease the bass. Press the up arrow in order to increase the bass. In order to adjust the treble, press the audio button until TRE appears on the display. The radio is now in the treble mode. Press the down arrow in order to decrease the treble. Press the up arrow in order to increase the treble. After either adjustment, the radio display will return to the clock after approximately 5 seconds.

Adjusting the Speaker Balance

In order to adjust the balance, press the audio button until BAL appears on the display. The radio is now in the balance mode. Press the down arrow in order to move the sound to the left speakers. Press the up arrow in order to move the sound to the right speakers. In order to adjust the fade mode, press the audio button until FAD appears on the display. The radio is now in the fade mode. Press the down arrow in order to move the sound to the rear speakers. Press the up arrow in order to move the sound to the front speakers. After either adjustment, the radio display will return to the clock after approximately 5 seconds.

Clock Operation

The clock function of this radio does not have a memory function. If power to the radio is interrupted, you will have to reset the clock.

Setting the Clock

In order to set the clock, the ignition switch must be in the ACC position or in the ON position. The radio may be turned on or off.

In order to set the hour:

  1. Press and hold the down arrow button (HR). After approximately 5 seconds a beep will sound, and the hour will advance.
  2. Release the button when the correct hour appears.

In order to set the minutes:

  1. Press and hold the up arrow button (MIN). After approximately 5 seconds a beep will sound, and the minutes will advance.
  2. Release the button when the correct minute appears.

Compact Disc Player Operation

This CD player plays only 120 mm (4.75 in) discs. Only use CDs with this symbol: COMPACT DISC DIGITAL AUDIO. If you insert any other disc, you may damage the CD player or the disc. Do not use 76 mm (3 in) discs. The discs are called CD singles.

Compact Disc Player Errors

ERR indicates an error, and the compact disc cannot play temporarily. The following conditions could cause the error:

    • The road is too rough. Play the disc when the road is smoother.
    • The disc is dirty, scratched, or wet.
    • The disc is upside down.
    • The air is very humid. If the air is humid, wait an hour.

Recall

Press the RCL/TUNE knob with a disc playing in order to toggle the following displays:

  1. The clock
  2. The CD message
  3. The track that is currently playing
  4. The elapsed time of the track that is playing

Pressing the knob once will change the display from the clock to the CD mode. Pressing the knob a second time within 2 seconds will change the display from the CD to the track number that is currently being played. Pressing the knob a third time within approximately 2 seconds will change the display again. The display changes from the track number that is currently being played to the elapsed time of that track number. If the knob is not pressed an additional time in 2 seconds, the display automatically will change modes. After approximately 5 seconds, the display will return to the clock.

Previous Track

If you press preset button 1 (PREV) once, the following actions will occur:

  1. The sound will mute.
  2. The CD player will move to the beginning of the previous track. For the correct operation of the previous selection function, the current track must have been playing for more than 10 seconds. If the current track has been playing for less than 10 seconds, then the CD will move to the beginning of the current track.

If you hold the button, or if you press the button more than once, the CD player will proceed through further tracks. The CD player will cycle backward if you hold the button. Each time you press and release the button, the CD player will move forward one track. The track number will appear on the display.

Next Track

If you press preset button 2 (NEXT) once, the following actions will occur:

  1. The sound will mute.
  2. The CD player will move to the beginning of the next track. For the correct operation of the next selection function, the current track must have been playing for more than 10 seconds. If the current track has been playing for less than 10 seconds, then the CD will move to the beginning of the current track.

If you hold the button, or if you press the button more than once, the CD player will proceed through further tracks. The CD player will cycle backward if you hold the button. Each time you press and release the button, the CD player will move forward one track. The track number will appear on the display.

Reverse

If you press preset button 3 (REV) once, the disc will rapidly return to a favorite passage. The current selection will remain audible at a lower sound level during the reverse mode. If you release the button, the CD player will play the passage at that point at normal sound. If you reach the beginning of the current selection, the previous selection will start.

Forward

If you press preset button 4 (FWD) once, the disc will advance quickly within a track. The current selection will remain audible at a lower sound level during the forward mode. If you release the button, the CD player will play the passage at that point at normal sound. If you reach the end of the current selection, the next selection will start.

Random Play

If you press preset button 5 (RDM) once, the CD player will play tracks in a random order. This feature will cancel if you press any of the following buttons:

    • The preset button 1 (PREV) that will play the previous selection to the track which was playing before the random mode began
    • The preset button 2 (NEXT) that will play the next selection to the track which was playing before the random mode began
    • The preset button 5 (RDM)
    • Preset button 6 (RPT)

The letters RND will appear on the display if this feature is active.

Repeat

If you press preset button 6 (RPT) once, the CD player will repeat a selection after the selection is finished playing. This feature will cancel if you press any of the following buttons:

    • The preset button 1 (PREV)
    • The preset button 2 (NEXT)
    • The preset button 5 (RDM)
    • The preset button 6 (RPT)
    • The AM/FM button

The letters RPT will appear on the display if this feature is active.

Cancel CD and Play Radio

If you press the AM/FM button while in the CD mode, you will cancel the CD operation. The unit will return to radio operation. In order to return to the CD mode, press the CD button.

Eject

The eject button has an up arrow and a line at the bottom. Press the eject button with the ignition switch in the ACC position or in the ON position in order to perform the following functions:

  1. Eject the CD.
  2. Change the sound to the radio, if the radio is turned on.

The CD player will start playing track 1 if the disc is inserted again. If the ignition switch is turned off, the eject function will still operate. The radio will remain off.

Circuit Operation

Ignition Positions

    • OFF
        The radio receives battery voltage at all times on the BLU/YEL wire through the DOME Fuse in order to keep the clock memory alive.
    • ACC or ON
         Voltage is applied to the GRY wire through the CIG Fuse in order to enable the radio operation. The radio is grounded through the G202.
       - The radio illumination is controlled by the instrument panel lamp dimmer.
       - The PARK or HEAD headlamp positions:
       - Voltage is applied through the dimmer control and to the radio panel lamp and the internal circuitry.

Compact Disc and Cassette Player

The compact disc (CD) or cassette player is part of the radio unit, if equipped. When operating, the same power required by the radio is necessary for the tape or CD player operation.