GM Service Manual Online
For 1990-2009 cars only
Table 1: Radio Features
Table 2: Cassette Features
Table 3: Compact Disc Features

The Entertainment System on this vehicle is configured with either a base or an uplevel system. Both the base and uplevel systems contain a radio, antenna, speakers.

The following list shows the radios available for this vehicle:

    • Uplevel Radio (UM7) - AM/FM Stereo
    • Uplevel Radio (UN6) - AM/FM Stereo, Cassette
    • Uplevel Radio (UL0) - AM/FM Stereo, Cassette, with Auto Tone Control
    • Uplevel Radio (UN0) - AM/FM Stereo, CD, with Auto Tone Control
    • Uplevel Radio (UP0) - AM/FM Stereo, Cassette, CD, with Auto Tone Control

Radio Features

Controls

Base UM7

Uplevel Cassette UN6

Uplevel Cassette UL0

Uplevel CD UN0

Uplevel Cassette, CD UP0

Power

Turn the VOLUME knob to turn the radio on.

Push the VOLUME knob to turn the radio on.

Volume

The volume is adjusted by rotating the VOLUME knob.

Tune

Turn the TUNE knob.

Press the up or down arrow on the TUNE button.

Seek

Momentarily press the right or left SEEK button.

Press the up or down arrow on the SEEK button.

Scan

Hold one of the SEEK buttons for at least 2 seconds.

Hold one of the SEEK arrows for at least 2 seconds.

Presets

Six AM, Six FM1 and Six FM2

Preset Scan

Press the P SCAN button to scan your presets.

Preset Saving

Press and hold the desired button until the sound mutes and then returns.

Set Clock

Press and hold the HRS until the correct hour appears. Press and hold the MIN button until the correct minute appears.

Recall

Push the VOLUME knob.

Press the RECALL button.

Balance

Turn the BAL control.

Press the BAL knob lightly so it extends. Turn the knob to adjust.

Fade

Turn the FADE control.

Press the FADE knob lightly so it extends. Turn the knob to adjust.

Bass

Press the BASS knob lightly so it extends. Turn the knob to adjust.

Treble

Press the TREB knob lightly so it extends. Turn the knob to adjust.

Auto Tone Control

N/A

Press the TONE button.

Cassette Features

Controls

Uplevel Cassette UN6

Uplevel Cassette UL0

Uplevel Cassette, CD UP0

Play

N/A

Press the SOURCE button to change to the tape function when the radio is on.

Press the SOURCE button to change to the tape function when the radio is on.

Stop

N/A

Press the AM-FM button to play the radio when a tape is in the player.

Press the AM-FM button to play the radio when a tape is in the player.

Eject

Press the eject button.

Press the eject button near the tape slot.

Forward

Press the right arrow button (preset 4).

Press the right arrow button (preset 4).

Reverse

Press the left arrow button (preset 3).

Press the left arrow button (preset 3).

Previous

Press the PREV button.

Press the PREV button.

Next

Press the NEXT button.

Press the NEXT button.

Changing Sides

Press the SIDE button to change the side of the tape that is playing.

Press the SIDE button to change the side of the tape that is playing.

Compact Disc Features

Controls

Uplevel CD UN0, and Uplevel Cassette, CD UP0

Remote CD Changer U1S

Play

Press the SOURCE button to change to the CD function when the radio is on.

Press the SOURCE button to change to the CD function if a magazine is loaded in the changer and the radio is on.

Stop

Press the AM-FM button to play the radio when a CD is loaded in the player.

Eject

Press the eject button near the CD slot.

N/A

Forward

Press the right arrow button (preset 4).

Reverse

Press the left arrow button (preset 3).

Previous

Press the PREV button.

Next

Press the NEXT button.

Random Order

Press the RAND button to hear the tracks in random order.

Press the RAND button to hear the discs and tracks in random order.

Next Disc

N/A

Press the SIDE button to advance to the next disc.

Recall

Press the RECALL button.

Each item in the list below represents topics covered in detail below.

    • AM/FM Reception
    • Antenna
    • Theftlock
    • Remote Playback Device
    • Steering Wheel Controls
    • Tape/CD Player Error Messages

AM/FM Reception

Radio Signal

The radio signal is sent from a broadcast station and is then received by an antenna. The strength of the signal received depends on the following:

    • The power output (wattage) of the broadcasting station
    • The location of the vehicle (or receiver) relative to the broadcast tower.
    • Obstacles between the tower and the receiver
    • Atmospheric conditions
    • What band (AM or FM) the station is broadcasting
    • Type of antenna and the ground plane

AM Reception

The AM band has a lower frequency range than the FM band. These longer wavelengths:

    • Bend around Obstacles
    • Follow the curvature of the earth
    • May reflect off the ionosphere (skip)

The AM frequencies have longer range due to the ground wave. The ground wave follows the curvature of the earth and is effected by its conductivity. Greater conductivity equates to less signal loss thus transmission over water is better than over land. The AM band has a range of 80-320 km (50-200 mi).

FM Reception

The shorter wavelengths of the higher frequency FM band:

    • Reflect off obstacles
    • Are absorbed by the ground
    • Penetrate the ionosphere

Broadcasts in the FM band are limited to "line of sight" reception which is typically 40 km (25 mi). Even when out of a direct line of sight, the signal may be reflected into areas that would be in a "shadow" otherwise. Factors which affect the line of sight include:

    • Height of the broadcast antenna
    • Height of the receiving antenna
    • Terrain and buildings in the broadcast path

Diversity Antenna System

The diversity antenna system uses both front and back windows with an integral antenna built between the glass layers of the windshield and as an applique to the rear glass. Any damage to the antenna requires replacing the glass.

A diversity antenna system is designed to deliver the best radio signal reception possible. Two antennas are used to form a diversity system. The primary antenna is part of the rear window and looks similar to the defogger grid. This antenna receives both AM an FM signals. The secondary antenna is part of the front windshield and receives only FM signals.

The antenna reception signals are sorted out by the radio antenna module. The radio antenna module is enabled when the radio is turned on. When the AM or FM band is selected on the radio, the antenna module connects the rear window antenna directly to the radio. In addition, when the FM band is selected an enable signal is sent to the antenna module. Superimposed on this enable signal is the strength of the signal being received by the radio tuner. The antenna module now performs two functions. It switches between the front and rear antennas, monitoring the radio signal strength and combines both signals and phase aligns them to create one strong signal.

Theft Deterrent

The "Theftlock" theft deterrent system is a feature on all base and uplevel radios. There is no need to program a security code into the radio as in past model years. The theft deterrent system now utilizes class 2 serial data to determine if the radio is in the appropriate vehicle. Each time the radio receives the "run" power mode message, it compares the VIN information it has stored to the VIN information received from a module on the class 2 serial data circuit responsible for transmitting that information. If a mis-match occurs, the radio display will indicate to the user the radio is locked. Once this takes place, a DTC will set, the radio will not respond to any button presses and become inoperative. The two scenarios able to cause this condition are:

    • A radio is installed from another vehicle
    • A module which communicates on the class 2 serial data circuit which supplies VIN information to the radio is replaced and not properly setup with the correct VIN information for that vehicle

The only way to unlock the radio is by using a scan tool. Always refer to the table in this section to diagnose the "Theftlock" DTC for further information.

Remote Playback Device

The remote playback device is a 12 disc remote CD changer. The radio controls and communicates with the remote playback device through Class 2 communication.

The remote CD changer allows for up to 12 compact discs to be played continuously. Normal size discs may be played using the trays supplied in the magazine. The magazine must first be loaded with discs before it can played. Press the button on the back of the magazine and pull gently on one of the trays. Load the trays from top to bottom, placing a disc on the tray label side up. If a disc is loaded label side down, the disc will not play and an error will occur. Gently push the tray back into the magazine. Repeat this procedure for loading up to 12 discs in the magazine. Once the discs are loaded into the magazine, slide open the door of the compact disc changer. Push the magazine into the changer in the direction of the arrow marked on the magazine. Close the door by sliding it all the way to the right. If the door is left partially open, the changer will not operate. When the door is closed, the changer will begin checking for discs in the magazine. This will continue for up to two minutes, depending on the number of discs loaded. To eject the magazine from the player, slide the CD changer door all the way open. The magazine will automatically eject. Whenever a CD magazine with discs is loaded in the changer, the CD changer symbol will appear on the radio display. If the CD changer is checking the magazine for CD's, the CD symbol will flash on the display until the changer is ready to play.

Steering Wheel Controls

Some audio functions are available using the steering wheel controls. The steering wheel controls consist of multiple momentary contact switches that connect a series of resistors. When a steering wheel control button is pressed, a specific resistance value is noted by the DIM. This results in a generated voltage, unique to the particular button. The DIM alerts the radio that the button has been pressed, and the radio responds, just as if the corresponding radio front panel button had been pressed.

Tape/CD Player Error Messages

The radio displays an error when any of the following occurs.

    • The radio will display error codes for the tape player, integral CD player, and remote CD changer.
    • The radio will display the following tape player error codes for tight tape, broken tape, and wrapped tape. If these conditions are detected, the radio will switch to the radio mode and eject the tape. The error code will be displayed for 5 seconds, followed by the tuner display, then the default.
       - E10-Tight tape.
       - E11-Broken tape.
       - E13-Communication problem.
       - E14-Wrapped tape.
    • The radio will display the following integral CD player error codes. If one of these problems is detected, the unit will switch to the radio mode and eject the CD. The display will show TOD, if the unit is off, or display the radio frequency for 5 seconds, then the default, if the unit is on.
       - E20-Optics focus error, may be due to moisture.
       - E21-Optics loss of tracking control, maybe due to blemishes on disc.
       - E22-Load/Unload motor problem.
       - E23-Communication problem.
    • The radio will display the following remote CD changer error codes. If one of these problems is detected, the unit will switch to the radio mode. The display will show TOD, if the unit is off, or display the radio frequency for 5 seconds, then the default, if the unit is on.
       - E30-Optics focus error, may be due to moisture.
       - E31-Optics loss of tracking control, may be due to blemishes on disc.
       - E34-Door Open.