GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Malibu 🢒 Body and Accessories 🢒 Entertainment 🢒 Radio/Audio System Description

Power Button (PWR) -- On/Off Switch

Important: When jump starting the vehicle, ensure that the radio is turned off in order to avoid damage to the sound system.

Depressing the PWR knob will alternately turn the radio to the ON or OFF position.

Volume Control (VOL)

The following factors describe the volume control:

    • A single multifunction rotary/push control provides both on-off power and volume control functions.
    • The volume control portion of the switch is a continuous rotary detent type with 36 detents per revolution.
    • Increase or decreae the volume over a range of 64 possible steps. This function will not be available during radio conditions that do not permit audio output (such as when seeking or scanning in tuner or tape modes.)
    • The volume control will function the same in both BOSE® and non-BOSE® applications.
    • Volume changes do not affect the radio display.
    • The volume function is replicated on the steering wheel control with separate volume buttons.
    • Each momentary button closure causes the volume to increase or decrease by one step. Pressing either button causes the volume to change at a rate of 12 steps per second.

Stereo Indicator

The word, STEREO (UM7), ST for all other models displays whenever a stereo broadcast is received.

Tune Control

The following factors describe tuning control:

    • The tuning control is a continuous rotary knob with 20 detents per revolution. This is a pop out knob on Oldsmobile models.
    • Tune the receiver by turning the control in the desired direction.
        Clockwise turning increases the frequency or amplitude.
        Counterclockwise turning decreases the frequency or amplitude.
    • Frequency or amplitude increases or decreases by one channel per detent.
    • Adjust the tuning control in order to stop the SEEK and SCAN functions. Tuning will then continue from the frequency that the receiver was at when the function was stopped.
    • The tuning function is replicated on the steering wheel controls with separate tune buttons (when equipped).

AM-FM Switching

The following factors describe AM-FM Switching:

    • The AM/FM button is a sequencing (push-push) type that toggles between the following bands:
       - AM
       - FM1
       - FM2
    • The button is active anytime the unit is in the ON position.
    • Depress the AM/FM button while in the receiver mode in order to change the tuning to the frequency last selected on the next band.
    • Depress the AM/FM button while in the playback mode in order to switch the unit into the receiver mode with the last selected band and frequency. The following band switching sequence begins from an initial state of FM1:
        1. The first push toggles the receiver to FM2.
        2. The second push toggles the receiver to AM.
        3. The third push toggles the receiver back to FM1.

Recall Button

Press the knob RCL, or the RECALL button, in order to alternate the display between the frequency or time information. With the ignition in the OFF position, press this button briefly in order to turn on the display with the time of day.

Bass and Treble Controls (Oldsmobile)

The following factors describe the Bass and Treble control on the Oldsmobile model:

    • The control is a 270 degree rotary pop-out/pull knob with the center detent that is shared between BASS and TREB (treble). Use this control in order to adjust the system's audio frequency response.
    • Operate the BASS function by first depressing and releasing the knob to the out position. This action affects only the lower audio frequencies and has a center frequency of 60 Hz.
    • Complete the following steps in order to operate the TREB function:
        1. Depress and release the knob to the out position.
        2. Pull the knob to the fully extended position.

This action affects the high audio frequencies and has a center frequency of 10k Hz.

    • The center position of a given control indicates a flat response over that particular frequency range.
        Move a control to the right of the center position in order to produce a boost.
        Move a control to the left of center in order to produce a cut in frequency range related to that control.
    • All units incorporate a loudness feature that automatically increases bass bias at low listening levels.
    • On Auto Tone Control (ATC) models, any adjustment of these controls will activate the manual tone control (ATC) mode. This action will establish the manual ATC mode as a default. The manual tone mode will display on the ATC models. The Bass and Treble changes on non-ATC models will not affect the radio display.

FADE Control (Oldsmobile)

The FADE control is a 270 degree rotary pop-out/pull knob with a center detent. The FADE Control shared with the balance function. The control adjusts the relative volume between the front and rear speakers. Use the following steps in order to operate the control:

    • Depress and release the knob to the out position.
    • Pull the knob to the fully extended position.
    • Rotate the knob clockwise in order to shift the volume from the rear speakers to the front speakers.
    • Rotate the knob counterclockwise in order to shift the volume from the front speakers to the rear speakers.
    • Fully rotate the knob in either direction in order to eliminate audio from the corresponding front or rear channels.
    • Depress and release the knob a second time in order to return the knob to the IN position.

Fade (BOSE® Applications)

This feature is called Spatial Fade in the BOSE® applications. The control performs the same function as the Fade Control (Oldsmobile) except that this control mainly affects the high audio frequencies. The following factors describe the operation of the Fade Control (BOSE® Applications):

    • A full rotation in either direction will eliminate audio from the corresponding front or rear channels (except for the subwoofer).
    • The following Fade functions will have no affect on the sub woofer:
       - Fade to front (other than the last step)
       - Fade to rear
    • The last step of fade to front will cut audio to the subwoofer completely.
    • Fade changes do not affect the radio display.

Balance (BAL) Control (Oldsmobile)

The following factors describe the Balance (BAL) Control (Oldsmobile):

    • The Balance (BAL) Control (Oldsmobile) is a 270 degree rotary pop-out/pull knob with center detent. The Balance (BAL) Control is shared with the Fade function.
    • The control adjusts the relative volume between the right and left speakers.
    • First, depress and release the knob to the OUT position in order to operate the control.
    • Rotating the knob clockwise in order to shift the volume from the left to right speakers.
    • Rotating the knob counterclockwise will cause a volume shift from right to left speakers.
    • A full rotation in either direction, will eliminate audio from the corresponding left or right channels.
    • Depressing and releasing the knob a second time will return the knob to the IN position (this control is active in the IN or OUT position).

Balance (BAL) Control (BOSE® Applications)

The BOSE® models have the same feature functionality for all channels except the subwoofer output. The subwoofer has the left and right audio summed together. The subwoofer will have the audio cut completely from the opposite channel at the last left and right balance steps only. The full right balance will cut the left audio channel to the subwoofer. Intermediate balance adjustments have no effect on the subwoofer output level. Balance changes do not affect the radio display.

Station Presets Buttons (Oldsmobile)

Favorite station preset push-buttons serve a dual role with cassette and compact disc player functions. When in the receiver mode, the push-buttons function as station memories. When a CD or tape deck is being played, the push-buttons perform the CD or Tape deck functions. Use the following steps in order to operate the station presets buttons:

    • Press or release any of the preset buttons in order to recall the following items:
      • That particular frequency
      • The ATC setting
      • The channel number
    • The following actions will occur while you are depressing the button:
      • The audio will mute
      • Any displayed channel number indicators will be extinguished
    • If the button is depressed for less than 2 seconds, the unit will tune to the desired preset upon release of the push-buttons. If this time is exceeded, the set mode will activate.
    • Five AM stations and 10 FM stations (using FM1 and FM2 bands) along with their respective ATC settings may be preset. Use the following procedure in order to preset the stations:
        1. Use one of the following controls in order to select a station:
   • TUNE
   • SEEK
   • SCAN
        2. Depress the desired preset button for at least 2 seconds.

The audio will mute and no channel number will display during this time period.

The return of audio and the channel number display indicates the new preset frequency has been stored.

        3. Release the button.
        4. The display will show the frequency and the channel number for 5 seconds after the preset is set.

Seek Buttons

Use the following information in order to operate the SEEK button on the UM7model:

    • Depress the SEEK button on the right-hand portion in order to seek up in frequency to the next strong station.
    • Depress the left-hand portion of the button in order to seek down in frequency to the next strong station.

Use the following information in order to operate the SEEK button on all other models. These models incorporate a vertically mounted SEEK button:

    • Depress the top portion of the button in order to seek up in frequency to the next strong station.
    • Depress the bottom portion of the button in order to seek down in frequency to the next strong station.

When equipped, the seek up portion of this function is replicated on the steering wheel control.

Scan Button

The SCAN push button is a momentary type control that is shared with the preset scan feature. Use the following information in order to operate the SCAN push-button:

    • Press the button in order to immediately mute the audio.
    • Release the button within 2 seconds in order to increase the frequency until a signal of sufficient strength enables stopping.
    • After stopping, the audio will unmute. The tuner will pause for 5 seconds before again muting and continuing scanning.
    • Scanning will stop under the following conditions:
      • You depress the SCAN button a second time
      • No stations are found after two complete band cycles
      • The receiver will then revert or stay tuned to the last frequency that was selected.

If the TUNE control is adjusted while scanning, the scan action cease and the frequency will change from the preset scanned frequency.

Preset Scan (Oldsmobile)

The Preset Scan is a hidden function on the radio. Use the following information in order to operate the Preset Scan function:

    • Press the SCAN push-button for a minimum of 2 seconds in order to activate the Preset Scan.
    • Press and hold the SCAN button in order to mute the audio. After a 2 second delay, the receiver will select the last preset selection initiated by the radio preset buttons.
    • If the receiver is tuned to a preset that was selected with either one of these buttons, the receiver will increment to the next preset selection.
    • The audio will unmute while the tuner pauses for 5 seconds before again muting and incrementing to the next preset.
    • The associated ATC mode will also be selected along with the preset.

Setting Time of Day
    • An initial delay of 2 seconds will occur after the first button depression, before the unit enters the time set mode and the time advances. Use the following push-buttons in order to set the time of day:
       - HR or HRS
       - MN or MIN
    • When you enter the time set mode, the display will show TOD along with one of the following items:
       - A (AM)
       - P (PM)
    • Depress HR or HRS in order to increase the hours.
    • Depress MN or MIN in order to increase minutes.
    • Reset the clock if the electrical power is interrupted by one of the following conditions:
       - A blown fuse
       - A discharged battery
       - Other conditions

Auto Tone Control

The TONE button is a sequencing (push-push) type switch. The TONE button switches between the predetermined frequency response curves and a manual mode (BASS and TREB controls functional). The following sequence will repeat in a continuous loop configuration:

  1. JAZZ
  2. VOCAL
  3. POP
  4. ROCK
  5. CLASSICAL
  6. MANUAL

When a specific ATC mode is selected with the tone button, the specific mode becomes the default. This ATC setting will be stored along with the receiver preset frequencies. Select the preset frequency in order to recall the setting.

The radio will display the graphical frequency response curve.