Table 1:	Radio Features
Table 2:	Compact Disc Features
Table 3:	XM Radio Messages

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, and speakers.

The uplevel system differs from the base level system by providing enhanced audio system features. These features may include the radio data system (RDS). The uplevel radio units are also OnStar® and XM Radio compatible.

The radio head includes the driver information display (DID). Driver information is provided to the radio head via GMLAN serial data link to the body control module (BCM).

The following list shows the radios available for this vehicle:

Speaker System

There are 2 speaker systems available on this vehicle and consist of the following components:

Base UQ4 System

4 Speaker System

Premium UQ3 System

7 Speaker System

Radio Features

Controls	Base U1C	Uplevel UN0	Uplevel US8
Power	Push the Power ON/OFF knob to turn the radio ON.
Volume	The volume is adjusted by rotating the POWER knob.
DISP (Display)	Press DISP knob to switch the display between time, temperature, or radio frequency	Press DISP knob to switch the display between time, temperature, or radio frequency. For RDS, press DISP knob to change what appears on the display while using RDS. For XM™, if equipped, press DISP knob while in XM mode to retrieve four different categories of information related to the current song or channel.
SCV	N/A	Press the AUTO VOL button. Adjust the SCV by pressing the AUTO VOL until the desired volume setting appears on the display. Three settings are available; LOW, MEDIUM, and HIGH.
Tune	Turn the DISP/ADJ knob.
Seek	Press the SEEK-SCAN UP button within 2 seconds for radio to find next strong signal, in current band, of increased frequency. Press the SEEK-SCAN DOWN button within 2 seconds for radio to find next strong signal, in current band, of decreased frequency.
Scan	Press and hold the SEEK-SCAN UP button longer than 2 seconds but less than 4 seconds. One audible beep is heard before it starts scanning.
Presets	Six AM, Six FM1 and Six FM2
Preset Saving	Press and hold any User Preset button (1-6) greater than 2 seconds. One audible beep is heard.
Preset Scan	Press and hold SEEK-SCAN UP or SEEK-SCAN DOWN button at least 4 seconds. Two audible beeps are heard before it starts preset scanning.
Mute	Steering Wheel Audio Controls only Press the MUTE button to silence the system. Press it again, or any other radio button, to restore the sound.
Fade or Balance	Push and release the BAL/FADE knob, within 2 seconds, to select and adjust w/Adj knob. Pushing and holding the BAL/FADE knob longer than 2 seconds, before a particular setting is displayed, produces one audible beep and sets the fade/balance settings to the center detent. The radio displays ALL CENTERED.
Bass, Treble or Midrange	Push and release the TONE knob, within 2 seconds, to select and adjust w/ADJ knob. Pushing and holding the TONE knob longer than 2 seconds, before a particular setting is displayed, produces one audible beep and sets the audio settings to the center detent. The radio displays ALL CENTERED.
Automatic Tone Control (ATC)	N/A	Press and release the AUTO EQ button to choose and program preset bass and treble equalization settings.

Set Clock Base (U1C) Radio

Set Hour Mode

Press and hold the CLOCK button until an audible beep is heard. The radio displays the clock icon, the time and the text ADJ HOUR when it enters the Set Hour Mode. The hours will flash. Turn the ADJ KNOB in increments to adjust the hour. Pressing and releasing the CLOCK button exits the Set Hour Mode and enters the Set Minute Mode.

Set Minute Mode

Press and hold the CLOCK button until an audible beep is heard. The radio displays the clock icon, the time and the text ADJ MIN when it enters the Set Minute Mode. The minutes will flash. Turn the ADJ KNOB in increments to adjust the minutes. Pressing and releasing the CLOCK button exits the Set Clock Mode and turns OFF the clock icon.

Set Clock Uplevel (UN0, UP0, UC6) Radio

Set Hour Mode

Press and hold the CLOCK button for less than 3 seconds. The radio displays the clock icon, the time and the text ADJ HOUR when it enters the Set Hour Mode. The hours will flash. Turn the ADJ KNOB in increments to adjust the hour. Pressing and releasing the CLOCK button for less than 3 seconds exits the Set Hour Mode and enters the Set Minute Mode. Pressing and holding the CLOCK button for 3 seconds or more exits the Set Hour Mode and enters the radio data system (RDS) Auto Set Clock Mode.

Set Minute Mode

Press and hold the CLOCK button for less than 3 seconds. The radio displays the clock icon, the time and the text ADJ MIN when it enters the Set Minute Mode. The minutes will flash. Turn the ADJ KNOB in increments to adjust the minutes. Pressing and releasing the CLOCK button for less than 3 seconds exits the Set Clock Mode and turns OFF the clock icon. Pressing and holding the CLOCK button for 3 seconds or more exits the Set Minute Mode and enters the RDS Auto Set Mode.

RDS Auto Set Mode

Pressing and holding the CLOCK button for 3 seconds or more enters the RDS Auto Set Mode. When the radio enters the RDS Auto Set Mode an audible beep is heard. If time information is available from RDS, the radio displays the new RDS time and the text UPDATED. If time information is not available, the radio displays the unchanged time and the text NO UPDATE.

To exit RDS Auto Set Mode, press and release the CLOCK button for less than 3 seconds, press any other non-clock function, or wait 5 seconds after pressing the CLOCK button or turning the ADJ KNOB.

Compact Disc Features

Controls	Base U1C	Uplevel UN0	Uplevel US8
Play/Stop	Press the AM/FM/CD button when listening to the radio to play a CD	Press the SRCE (source) button when listening to the radio to play a CD.
Eject	Pressing the EJECT button when CD is active or not active ejects the CD. Pressing this button with no CD loaded will load a CD. After loading, CD becomes active audio source.			Press and hold the EJECT button for less than 2 seconds to enter the single CD eject mode. Press and hold the EJECT button for more than 2 seconds to enter the all CD eject mode.
Forward	Pressing and holding the FWD button for 2 seconds plays the CD 6-10 times the normal speed. Pressing and holding the FWD button greater than 2 seconds plays the CD 15-30 times the normal speed. During the fast forward mode the radio will reduce audio output by 6 dB.
Reverse	Pressing and holding the REV button for 2 seconds plays the CD 6-10 times the normal speed in reverse. Pressing and holding the REV button greater than 2 seconds plays the CD 15-30 times the normal speed in reverse. During the reverse mode the radio will reduce audio output by 6 dB.
Previous	Press and release the down arrow on SEEK/SCAN button for 2 seconds or less and the elapsed time of the track is greater than 8 seconds, the radio will seek play the beginning of the current CD track. Press and release the down arrow on SEEK/SCAN button for 2 seconds or less and the elapsed time of the track is less than 8 seconds, the radio will go to the previous track. Press and release the down arrow on SEEK/SCAN button a number of times and the radio will seek back the number of tracks equal to the number of button presses.
Next	Press and release the up arrow once on SEEK/SCAN button within 2 seconds and the radio will seek the beginning of the next CD track. Press and release the up arrow on the SEEK/SCAN button a number of times and the radio will seek forward a number of tracks equal to number of button presses.
CD Track Scan	Press and release the SEEK (U1C), SEEK/SCAN (UN0, US8) or SEEK SCAN UP/DOWN button for more than 2 seconds. The radio produces an audible beep and will scan up to the next track and play the first 10 seconds. Will continue to scan the first 10 seconds of each track until all the tracks on the disk or the scan is stopped.
Repeat	Press and release the RPT button to enter the repeat selection mode. When the track ends, the radio will play the same track on the CD from the beginning. Press and release the RPT button while in the repeat mode to exit.
Random	Press the RDM button to enter the random access mode. The radio will pick the tracks to play in random order. Press the EJECT or RDM button to exit the random access mode.			Press and release the RDM button within 2 seconds to enter the single disc random access mode. The radio will pick the tracks to play in random order.

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

AM/FM Reception

Radio Signal

A radio broadcast station uses a transmitter to send radio signals radiated from an antenna. A receiver uses an antenna to capture the radio signals. The strength of the signal depends on the following factors:

AM Reception

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

The AM frequencies have longer range due to the ground wave. The ground wave follows the curvature of the earth and is affected 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 miles).

FM Reception

The shorter wavelengths of the higher frequency FM band:

Broadcasts in the FM band are limited to "line of sight" reception which is typically 40 km (25 miles). 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:

Theft Deterrent

The Theftlock theft deterrent system is a feature on all base and uplevel radios. The theft deterrent system utilizes GMLAN serial data to determine if the radio is in the appropriate vehicle. Each time the radio receives the VIN packet message and is in the RUN power mode, it compares the VIN information it has stored to the received VIN packet message containing VIN information. The radio receives this message from a module on the GMLAN 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, the radio will not respond to any button presses and become inoperative. The 2 scenarios able to cause this condition are:

The only way to unlock the radio is by using a scan tool. The scan tool sends the appropriate diagnostic message (relearn VIN) to reset the radio. Using a scan tool, select the radio VIN relearn procedure from the module replacement screen in Vehicle Control Systems.

Removing CDs

Use the eject button, the button labeled CD, to remove a disc.

To remove a single disc, press and release the EJECT button within 2 seconds. The message REMOVE CD is displayed.

Seek (SEEK)

Press the SEEK button in order to seek to the next higher or lower station. The sound will mute when seeking another frequency. The SEEK button is inactive when the front radio is in the SEEK mode.

Power (PWR)

Press the PWR push button in order to turn the rear seat audio system ON or OFF. The rear speakers mute when the power is turned ON. The rear seat audio functions are operable even when the primary radio power is OFF.

Band Switching (AM/FM)

Press the AM/FM push button in order to select between (AM and FM) or (AM, FM1 and FM2) for radios with 2 FM bands. The selection appears on the display. If the front passengers are already listening to AM-FM, the rear seat audio controller will not switch between the bands and cannot change the frequency.

Source Switching (TAPE CD)

Press the TAPE CD push button in order to activate the source switching feature. There must be a cassette tape and/or compact disc in the player.

Preset Program (P.SET PROG)

Press the P.SET PROG button in order to select between pre-programmed station presets. The front passenger must be listening to something different for the P.SET PROG to operate.

Volume (VOL)

Rotate the volume control in order to increase or decrease the volume. The top VOL knob controls the top headphone and the bottom VOL knob controls the bottom headphone.

Radio Data System (RDS)

All uplevel audio systems are equipped with technology known as the radio data system (RDS). RDS is a system that sends data along with the audio of the FM station you are currently tuned to. RDS is a standard that defines how a FM broadcast station may send digital data along with the audio program. Think of it as a one way wireless modem, allowing the broadcaster to send information about his program to your receiver.

RDS data is carried in what is known as a subcarrier. A subcarrier is a frequency that the FM broadcaster is authorized to use to send data or other audio programs that are not audible in the main audio program. RDS information can be used to display program information and to control the radio.

To receive the RDS signal, all that is needed is an FM receiver with a RDS circuit. A special integrated circuit capable of dealing with the RDS signal is in the RDS circuit and passes it along to the receiver's microprocessor where it is decoded and acted upon.

RDS Basic Information

In some cases, a radio station broadcasting incorrect information may cause the RDS features of the radio to appear to work improperly.

Displaying RDS Information

The RDS feature is always ON. When tuned to a non-RDS station, the radio will display frequency information as you would normally expect. When tuned to a RDS station, the radio can operate as follows:

Viewing and Selecting RDS Information for Display

Press the P-Type knob to enter the program type mode. The radio displays the last program type selected.

Using RDS Program Types to Tune Radio

Listed are several ways on how to tune your radio using RDS program types.

The radio will now be configured to tune based on RDS data rather than frequency.

A Fast Way to Find a RDS Station In Your Listening Area

1. Press the P-TYPE button, the radio displays the current P-Type to search for.
2. Rotating the ADJ knob scrolls through a display of all available program types.
3. The program type selected becomes the active program type.

Finding a RDS Station By Specific Program Type

1. Press the PROG TYPE or P-TYPE button, the radio will display the current P-Type to search for.
2. Rotate the TUNE knob until the desired program type is shown in the display.
3. Press the PROG TYPE or P-TYPE button and the radio will now seek the first RDS Broadcaster of the selected P-Type.

If the radio cannot find the desired P-Type, the radio displays "NONE" and will return to the last station you were listening to.

Using the INFO Feature

When the INFO icon appears in the radio display, a new text message is available for viewing. These text messages are from the RDS broadcaster to the listening public and may be general information such as artist and song title, call in phone numbers, etc.

How to View the INFO Message

Controlling the Radio

RDS can control the radio when data the receiver can use responds to timely information performing the following:

Using the RDS Traffic Feature

Some RDS broadcasters may carry traffic information programming to inform you of current traffic conditions in your listening area and is indicated by the TRAF icon in the radio display. RDS enables the broadcaster to get this information to you even when you are listening to a tape or compact disc. This feature can be enabled or disabled by the listener. Press the TRAF button to find a station that claims to carry traffic information. You may do this even when playing a cassette tape or compact disc. This action will operate in the background without interrupting the current playback. If the radio is not currently tuned to an RDS traffic station, the radio will immediately seek an RDS traffic station. If the radio finds an RDS traffic station, the TRAF icon will appear on the radio display as will brackets around the [TRAF] icon. If the radio cannot find an RDS traffic station after searching through the entire FM band, the radio will display NO TRAFFIC.

Traffic Interrupt Feature

Whenever the TRAF icon is displayed, the current FM station may also broadcast traffic announcements. Traffic announcements are reports of the current traffic conditions in the listening area of the tuned FM broadcasters.

Your radio can interrupt the playback of a cassette or compact disc by use of the traffic interrupt feature. The traffic interrupt feature is enabled when the TRAF icon is displayed.

If the broadcaster sends out a traffic announcement while you are listening to FM or in the playback mode, TRAFFIC will be displayed on the radio and the audio from the broadcaster will be heard. At the conclusion of the traffic announcement, the radio will return to the previous playback mode.

During the time the radio displays TRAFFIC, you can adjust the volume of the traffic announcement. This will be the volume at which all future traffic announcements will be heard.

You can also interrupt a traffic announcement interrupt by pressing the TRAF button.

RDS Program Type Interrupts

When the program type feature is ON, all program types may be selected as interrupts. Perform the following to select a program type as an interrupt.

1. Turn ON the radio.
2. Select the program type.
3. Press and hold the program type button, labeled PROG TYPE or P-TYPE, for 2 seconds while the program type is displayed.

When an interrupt is set, the display shows the program type followed by an asterisk and the brackets around the [P-TYPE] icon are illuminated.

To turn an interrupt OFF:

1. Select a program type marked as an interrupt.
2. Press and hold the program type button, labeled PROG TYPE or P-TYPE, for 2 seconds. The program type will be unmarked by turning OFF the asterisk. If no other program type interrupts are set, the brackets around the [P-TYPE] icon are also turned OFF.

When a program type interrupt is set, the radio will wait for the current FM RDS station to change its program type to one of those selected as an interrupt. When the station program type changes to a program type interrupt setting then the interrupt is activated. If the radio is in a playback mode, an interrupt will cause the radio to switch to the FM band, display the program type followed by INT, and adjust the volume to the last active interrupt volume. If the radio is in the FM mode when an interrupt occurs, only the volume will change. The radio resumes the mode that was active prior to the interrupt, when an interrupt ends. An interrupt in progress may be canceled by pressing the program type button or a mode button.

During a national or local emergency, a special program type interrupt message ALERT! is displayed. This special announcement will cancel all other RDS features that are in progress, such as a traffic announcement.

Alternate Frequency (AF) Switching

RDS permits broadcasters to send information to the radio that allows the radio to automatically switch frequency to the best quality station in that broadcasters network.

Since the radio is displaying the broadcaster call letters or nickname, the listener will not see the frequency during an AF switch unless you have changed the default display to be frequency instead of Program Service name.

To enable or disable AF switching perform the following:

When AF is enabled and you recall a RDS station stored on preset, the radio determines if the station stored is of acceptable quality. If not, the radio checks all available AFs for your station. If the radio fails to locate your program, AF SEARCH will be displayed as the radio scans across the band looking for your program or an affiliated network. If the radio cannot find the original station or an acceptable alternate frequency NOT FOUND will be displayed and the radio returns to the original frequency for the preset.

RDS Clock Time

Broadcasters can choose to send clock time information in the RDS data. This information can be used to update the clock time on the radio. RDS clock time is broadcast once a minute. To set the clock using RDS clock data perform the following:

Steering Wheel Audio Controls

Some audio functions are available using the steering wheel controls. The steering wheel controls are actually a resistor network which consists of multiple momentary contact switches and a series of resistors. The switches and resistor network is arranged so that each switch has a different resistance value. When a switch is pressed, a voltage drop occurs in the resistor network which produces a specific voltage value unique to the switch selected. These specific voltage values allow the radio to identify which switch has been pressed. The radio responds just as if the corresponding radio front panel button had been pressed.

When the radio is ON, the radio supplies approximately 10 volts to the switches on the 10-volt reference circuit. The specific voltage signal from the switch is returned to the radio on the steering wheel controls signal circuit.

XM Satellite Radio

XM is a national satellite radio service that offers up to 100 coast to coast channels including music, news, sports, talk and children's programming. XM provides digital quality audio and text information, including song title and artist name. A service fee is required in order to receive the XM service. For more information, contact XM at www.xmradio.com or call 1-800-556-3600.

Digital Radio Receiver

The radio communicates with the digital radio receiver (DRR) via the GMLAN data bus. When the radio communicates with the DRR, the virtual network (VN INFOTAINMENT) is activated by the radio. During this communication phase, the radio sends a specific GMLAN frame message to establish a link with the DRR. The DRR responds with a specific frame message back to the radio confirming the link was successful. The scan tool can be used to check if any remote device is connected to the radio. In this case, observe the RSE parameter in the Radio Data Display. The scan tool will indicate RSE - Present. When a XMI or XM2 frequency setting is selected from pressing a button on the radio, a specific GMLAN frame message is sent to the DRR to change to the selected frequency. During XM operation the audio signals are sent over the left and right audio signal circuits from the DRR to the radio.

Viewing Messages

Press the DISP or RCL button while in XM mode to view various pieces of information related to the current song or channel. By pressing and releasing the DISP or RCL button, you may view four different categories of information: Artist Name/Feature, Song/Program Title, Channel Category, and other Additional Information that may be broadcast on that channel. Additional Information messages may not always be available. If an Additional Information message is being broadcast on the tuned channel, the INFO icon will appear on the display. Each of the four information types may have multiple pages of text. To reach a category, press and release the DISP or RCL button consecutively until the desired type is displayed. If there are multiple pages of text for the selected information type, the radio will automatically display all the pages for that type at a rate of approximately one page every three seconds before timing out and returning to the default display. You may override this feature by pressing the DISP or RCL button to review all of the pages at your own pace.

XM Radio Messages

Radio Display Message	Condition
Updating	Updating encryption code
No Signal	Loss of signal
Loading XM	Acquiring channel audio (after 4 second delay)
Off Air	Channel not in service
CH Unavl	Channel no longer available
No Info	Artist Name/Feature not available
No Info	Song/Program Title not available
No Info	Category name not available
No Info	No text/informational message available
Not Found	No channel available for the chosen category
XM Lock	Theft Lock active
Radio ID	Radio ID label (channel 0)
Unknown	Radio ID not known (should only be if hardware failure)
Check DAB	Hardware failure

Radio Circuit Operation

Radio Power: The main radio power is supplied by the 10-amp RADIO fuse located in the body control module (BCM). The radio does not use a discrete ignition feed circuit for power moding. The power mode master (PMM) provides the system power mode to the radio via GMLAN signals. The PMM determines the system power mode by processing power mode information from ignition switch inputs. GMLAN vehicle power modes supported by the radio are OFF, ACCESSORY, RUN, and CRANK REQUEST.

Radio Grounds: The main radio ground provides a ground for the radio circuits. The radio is also case grounded.

Radio Data Link Communication: The radio communicates with other modules via the GMLAN data bus which is a CAN based protocol. This vehicle uses 2 variants of the GMLAN data bus. The variants are a low speed and high speed vehicle bus. The radio connects to the low speed vehicle bus which runs between 12.5-40 kbps.

Radio Head Unit Dimming: Dimming and backlighting levels are determined by the GMLAN signal data the radio receives. The radio sets the backlight and VF display dimming to the value indicated by the interior dimming level and interior dimming display level signals in the GMLAN dimming information frame. The radio provides faceplate and control/graphics backlighting in the OFF (RAP inactive) when the exterior lighting VN is activated. The radio display is consistent then with the surrounding devices that use analog PWM dimming to backlight their control/graphics when the power mode is OFF and the park lights are ON.