Battery positive voltage is provided to the radio from the RDO/INTLP/ONSTAR fuse in the fuse block--I/P. The radio is grounded to G302 and G303. The radio is enabled/disabled by class 2 messages from the body control module (BCM).

The Entertainment System on this vehicle is configured with a base and uplevel system. The base and uplevel systems contain a radio, antenna, speakers, and on some vehicle lines an audio amplifier.

The uplevel system differs from the base system by providing the customer with enhanced audio system features. Some of those features may include the radio data system (RDS), an audio amplifier and programmable equalizer (EQ). Satellite digital radio (U2K) is available with uplevel systems.

The following list shows the radios available for this vehicle:

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

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:

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 mi).

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 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:

XM satellite radio provides digital radio reception. The XM signal is broadcast from two satellites and, where necessary, terrestrial repeaters. The high power satellites allow the antenna to receive the XM signal even when foliage and other partial obstructions block the antennas view of the satellite. Terrestrial repeaters are used in dense urban areas. These repeaters will receive the satellite signal and re-broadcast them at much higher power levels in order to ensure reception in areas with densely packed tall buildings.

The antenna is comprised of a fixed mast which is mounted on the body of the vehicle. Mast antennas are located typically on the fender or rear quarter panel of the vehicle.

The purpose of an amplifier is to increase the power of a voltage or current signal. The output signal of an amplifier may consist of the same frequencies as the input signal or it may consist of only a portion of the frequencies of the input signal, as in the case of a subwoofer or a mid-range amplifier.

When the radio is turned on, the radio sends a voltage signal to the audio amplifier via the radio on signal circuit. The gain control signal circuit allows the radio to recognize that an amplifier is present. Once the radio detects the amplifier, the radio will output low level audio signals to the amplifier. With the amplifier enabled, the signal that drives the speaker is now amplified.

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:

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.

With this feature, your vehicle will recall the latest radio settings as adjusted the last time your vehicle was operated. This feature allows 2 different drivers to store and recall their own radio settings for AM and FM presets, last tuned station, volume, tone and audio source --radio, cassette or CD. The settings recalled by the radio are determined by which transmitter was used to enter the vehicle. After the UNLOCK button is pressed on the transmitter and the ignition is in RUN, the radio settings will automatically adjust to where they were last set by the identified driver. All vehicles are shipped with this feature on. This feature can be disabled by your dealer if desired. Refer to Driver Personalization in Personalization.

The remote playback device is either installed at the factory or in some instances it is dealer installed. There are 3 types of remote playback devices, a multi disc remote CD changer, a single disc CD player and a cassette player. All 3 devices have a wiring harness which plugs into the back of the radio. The radio controls and communicates with the remote playback device through a Entertainment and Comfort (E&C) or Class 2 communication circuit.

Remote CD Changer (CDX)

The remote CD changer allows for multiple compact disks to be played continuously without having to manually change compact discs. Normal size discs may be played using the slots supplied in the magazine. The magazine must first be loaded with discs before it can played. To load CD's, insert the CDs from bottom to top, placing the discs in the magazine label side up. If a disc is loaded label side down, the disc will not play and an error will occur. Care should be used to align and insert the disc into one disc tray only. Repeat this procedure for loading all of the discs in the magazine. Once the discs are loaded into the magazine, push the magazine into the changer in the direction of the arrow marked on the magazine. When the CD magazine is loaded, the changer will begin checking for discs in the magazine. This will continue for up to one and a half minutes, depending on the number of discs loaded. To eject the magazine from the player, push the CD changer door. The door will open. Then press the eject button. 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 CDs, the CD symbol will flash on the display until the changer is ready to play.

Important: If the CD magazine fails to eject after the EJECT button has been pressed, do not attempt to pry the magazine from the CD changer.

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 the 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 an 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 an RDS station, the radio can operate as follows:

Viewing and Selecting RDS Information for Display

Press the TUNE knob once for less than 2 seconds when the radio displays the program service (PS) name and the frequency of the station will be displayed. Press the knob again, and the program type (P-Type) will be displayed. Pressed again, and the program type (PTY) name will be displayed, if the broadcaster is broadcasting one. The PTY name is an eight-character name that the broadcaster may use to further identify the type of programming currently being broadcast. Should you decide that Frequency, P-Type or PTY name is more desirable to display when tuned to an RDS station than the PS name, press the TUNE knob until the desired information is displayed, then press and hold for more than 2 seconds. A beep should be heard and the radio will now display the selected information whenever tuned to an RDS broadcaster. The radio will display frequency for all non-RDS broadcast stations.

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 PROG TYPE or P-TYPE button, the radio displays the current P-Type to search for.
2. Rotate the TUNE SELECT RCL knob until the radio displays "ANY TYPE". Press the SEEK SCAN button again and the radio will now seek the first RDS Broadcaster of any kind that it can find in the FM band.

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 SELECT RCL knob until the desired program type is shown in the display.
3. Press the SEEK SCAN 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 "NOT FOUND" 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 until the volume during another traffic announcement.

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 broadcaster's to send information to the radio that allows the radio to automatically switch frequency to the best quality station in that broadcaster's 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 an RDS station stored on preset, the radio determines if the station stored is of acceptable quality. If not, the radio checks all available AF's 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 broadcasted once a minute. To set the clock using RDS clock data perform the following:

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 1-800-852-9696.

Digital Radio Receiver

The radio controls communicate with the digital radio receiver via the class 2 communication circuit. The digital radio receiver sends remote radio audio signals 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.

Important: Radio chime level adjustment is only available on radios equipped with RDS.

The radio is the vehicle chime producer. The chime is audible from the driver's side front door speakers.

To adjust the chime level louder.

1. Turn ON the ignition.
2. Turn OFF the radio.
3. Press and hold preset button 6.

The chime volume level will change from the normal level to loud. The radio displays "LOUD".

To change back to the default or normal setting follow the previous steps. The chime volume level will change from the loud level to normal. The radio displays "NORMAL".

Each time the chime volume is changed, the radio sounds three chimes as an example of the new volume selected.

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