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, and an audio amplifier.

The uplevel system differs from the base level system by providing the customer with enhanced audio system features. Some of those features include the radio data system (RDS), extended range speakers, an uplevel amplifier, digital signal processing, and weather capabilities.

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 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 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:

XM Satellite Radio

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 ares. 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.

This vehicle has a scanning diversity AM/FM antenna system. This system consists of the following parts:

1. 3 Antenna Grid Patterns on the rear window interfacing with the rear defog grid.
2. AM/FM Antenna Module
3. Coax - The radio sends a 12  volt signal to module when in FM mode (less than 1 volt in AM and WX mode). The radio also sends feedback on signal quality to module in FM mode.
4. 12V power feed from the Radio to the Antenna Module 0.35 pink wire with single pin connector. The 12V power feed from the radio to the AM/FM antenna module is on any time the radio is on.
5. Radio

In AM and WX mode the system functions as follows:

The AM/FM antenna module takes the signal from only the AM/FM1 antenna pattern on the rear window. The AM/FM antenna module amplifies this signal and sends it to the radio. In this mode the radio does not supply any voltage to the center conductor of the coax and there is no feedback signal present on the coax.

In FM mode the system functions as follows:

The AM/FM antenna module takes the best signal from one of the three (3) FM antenna patterns on the rear window. The AM/FM antenna module amplifies this signal and sends it to the radio. In this mode the radio supplies 12V to the center conductor of the coax and this switches the module into FM mode. The radio also supplies a feedback signal, along the coax, to the AM/FM antenna module, which indicates the quality of the signal. Based on measured input signal level and the feedback from the radio the AM/FM antenna module switches between the 3 antennas to find the best signal.

Important: While operating the power folding top, the amplifier will mute momentarily to adjust the equalization settings.

The radio or digital radio receiver(routed through the radio), and Onstar® supplies low level audio signals to the audio amplifier in order to boost the signal sent to the speakers.

The radio uses the antenna input signal to create a stereo audio output signal, which is sent at the user-defined volume level to the audio amplifier. The audio amplifier amplifies the signal and sends it to the appropriate speakers. Tone, balance and fade information is sent by the radio to the audio amplifier via the GMLAN communication circuit. Additional output processing is provided by the noise-canceling microphone. The microphone monitors interior ambient noise allowing the audio amplifier to modify the audio output. This maintains the sound at an enjoyable level.

Radio

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 GMLAN 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 the instrument panel module (IPM) on the GMLAN circuit. 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:

1. A radio is installed from another vehicle
2. The IPM 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.

Digital Radio Receiver

The digital radio receiver utilizes GMLAN to determine if it is in the appropriate vehicle. Each time the digital radio receiver receives the "run" power mode message, it compares the VIN information received from the instrument panel module (IPM) on the GMLAN circuit. If a mis-match occurs, the radio display will indicate to the user the digital radio receiver is locked. This will occur if a digital radio receiver is installed from another vehicle. The digital radio receiver cannot be unlocked, it must be replaced.

This feature allows 2 different drivers to store and recall specific radio settings. The settings recalled by the radio are determined by which remote keyless entry (RKE) transmitter (1 or 2) is used to enter the vehicle. The number on the back of the RKE transmitter corresponds to driver 1 or driver 2. The radio settings automatically adjust to where they were last set by the identified driver. The settings can also be recalled by briefly pressing the MEMORY seat button 1 or button 2 located on the drivers door.

The radio can store home and away presets. Home and away presets allow you to use 1 set of preset radio settings in the area where you live, and another set when you go out of town. That way, you do not need to reprogram your presets every time you travel. With the radio off and the clock displayed, use FF and RW to select home or away presets. In order to select the away presets, press and hold FF for 5 counts until you hear a beep. The next time the radio comes on, the away presets are active. In order to select the home presets, press and hold RW for 5 counts until you hear a beep. The next time the radio comes on, the home presets are active.

When battery power is removed and later applied, you do not have to reset your home radio presets because the radio remembers the presets. However, you do have to reset the away radio presets.

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

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.

Broadcast RDS information can be used in a variety of ways by the receiver and listener, but basically falls into two categories: Display and Control.

Displaying Program Information

RDS displays textual information such as:

Finding an RDS Station

To find an RDS station press the RDS button. The radio will seek to the next RDS station.

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 TA 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 TA 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, TA will appear in the radio display. If the radio cannot find an RDS traffic station after searching through the entire FM band, the radio will display NO TRAFFIC STATION FOUND.

Viewing Messages

When MSG appears on the radio display, a new message is available for viewing. These messages are from the RDS broadcaster and may be general information such as artist and song title. To view the text message, press the MSG button. If the whole message does not appear on the display, parts of the message will appear every three seconds until the message is completed. To view the message faster, press the MSG button again.

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 press the RDS SELECT button. Then press and hold either the HR or MN button. If the broadcaster is sending clock time data the display should show STATION TIME IS xx:xx. If the time is acceptable, simply continue to press and hold the HR or MN button until the display shows TIME UPDATED.

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 instrument panel module (IPM). This results in a generated voltage, unique to the particular button. The IPM alerts the radio via GMLAN message that the button has been pressed, and the radio responds, just as if the corresponding radio front panel button had been pressed.

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 GMLAN communication circuit. The digital rdio receiver sends low level audio signals to the audio amplifier.

Viewing Messages

Press the MSG button while in XM mode to view various pieces of information related to the current song or channel. By pressing and releasing the MSG 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, MSG 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 MSG 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 MSG button to review all of the pages at your own pace.

Selecting a PTY

The LEVEL + or - buttons can be used to scroll through the list of available program types (PTY). Press the PTY button, followed by the LEVEL + or - buttons to scroll through the available program types. When the desired PTY is shown on the display, press the TUNE/SEEK or SCAN button twice. The radio will seek the next station of that type.