For 1990-2009 cars

Table 1: | Radio Function
Table 2: | Disc Function

This vehicle entertainment system is equipped with the configuration including radio, antenna, speaker and audio amplifier.

#### Radio Function

Band | Press the softkey to select AM1, AM2, AM3, FM1, FM2, FM3.
Power Supply | Press PWR/VOL knob to turn on the radio.
Preset | 5AM1, 5AM2, 5AM3, 5FM1, 5FM2, 5FM3
Preset Station | Perform by lightly touching the ALL softkey at the center of the screen.
Scan | Press and hold the UP/DOWN arrows used for searching.
Search | Press the UP/DOWN arrows used for searching.
Softkey | Multiple touch screen buttons, used to control and operate the navigation and audio system
SRCE | Switch the audio modes in order: AM -> FM -> TV -> CD/DVD -> External Video/Audio (AUX)
Tune | Rotate the knob to select the frequency.
Volume | The volume can be adjusted by rotating the Power/Volume knob.

#### Disc Function

Disc moved downward | Click the screen softkey
Disc moved upward | Click the screen softkey
Eject | Press and release in order to eject a single CD. Press and hold to eject all the CD.
Load | Press and release in order to load a single CD. Press and hold to load all the CD.
Next Track | Press the UP arrow used for searching or rotate the right knob clockwise.
Previous Track | Press the DOWN arrow used for searching or rotate the right knob counterclockwise.
Fast Forward/Fast Backward | Click the screen softkey

The listed following will be described in details in the content.

• | Radio Reception

• | Diversity Antenna System

• | Audio Amplifier

• | Theft Lock

• | Remote Player

• | Steering Wheel Control

• | Rear Seat Audio Control (RSA)

• | Infrared Remote Control

• | Wired Headphone Jack

### Radio 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. The greater conductivity, the 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:

• | 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 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:

• | Height of the broadcast antenna

• | Height of the receiving antenna

• | Terrain and buildings in the broadcast path

### Diversity Antenna System

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.

### Audio Amplifier

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.

### Theft Lock

#### Radio

Content theft deterrent system is a function equipped with all the common and high class 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 mismatch occurs, the radio display will indicate to the user the radio is locked. Once this takes place, a DTC will set and 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 DIM 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. For further information, always refer to Diagnostic Table in this section for diagnosing the theft lock DTC.

### Steering Wheel Controls

Some audio functions are available to control by 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 allows the button to produce a voltage. 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.

### Rear Seat Audio (RSA)

The RSA is incorporated into the HVAC control module. Audio, video sources and speaker control are all performed by the amplifier and radio via serial data communication. The RSA system includes a control panel, two headrest displays, two earphone jacks and a remote control.

### Infrared Remote Control

When the audio control function is turned on for the RSA system, the infrared remote control can be used to control the sound source playback and display mode of the front or rear seat. In Front Control mode, the sound source playback of front/rear seat and the display mode of rear seat monitors can be controlled simultaneously; in Earphone Control mode, the sound source playback of rear seat and the display mode of the headrest display can be controlled.

### Wired Headphone Jack

The preset control station is equipped with 2 wired headphone jacks. The headphone can be used to listen in the RSA audio function. Insert the headphone into the jacks in order to use the wired headphone. Using the left or right headphone button on RSA panel to adjust the volume, and the visual indicator on the RSA display will indicate a volume level.