Radio/Audio System 1

RADIO/AUDIO SYSTEM DESCRIPTION AND OPERATION

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. An audio amplifier and digital radio reception (U2K) is available with the uplevel systems. Radio data system (RDS) is standard on all radios.

The following list shows the radios available for this vehicle:
- Base Radio (U1P)-AM/FM Stereo, CD with Programmable Equalizer, and RDS
- Uplevel Radio (US8)-AM/FM Stereo, CD MP3 with Programmable Equalizer, and RDS
- Uplevel Radio (UC6)-AM/FM Stereo, Integral CD changer (ICDX) with Progammable Equalizer, and RDS

MP3 Features:

MP3 FEATURES

Each item in the list below represents topics covered in detail below.
- AM/FM Reception
- XM Reception
- Antenna
- Audio Amplifier
- Theft Deterrent
- Integral CD Changer (ICDX)
- Radio Data System (RDS)
- XM Satellite Radio
- XM Advisory Messages
- Radio Chime Level Adjustment
- 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, or 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
- Which 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, or skip, off of the ionosphere

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:
- 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

XM Reception
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.

Antenna
The antenna system is a rear window defogger grid antenna. Using the defogger grid as an antenna requires circuitry to decouple the RF from the DC heater current. This is accomplished by the radio antenna module.

Audio Amplifier
The purpose of an audio 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 input frequencies, as in the case of a subwoofer or a mid-range amplifier.

Power is supplied to the audio amplifier via the RADIO/AMPLIFIER fuse in the IP fuse Block. Ground is provided to the amplifier via G202. When the radio is turned on, and an amplifier is detected via the amplifier present signal, the radio sends a voltage signal to the audio amplifier via the antenna enable circuit. This circuit enables the audio amplifier to amplify the speaker output circuits from the radio. The audio amplifier sends the speaker output signals to drive the appropriate speakers.

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 to diagnose the "Theftlock" DTC for further information.

Integral CD Changer (ICDX)
The Integral CD Changer has the capability of storing and playing up to six (6) compact discs. The ICDX has a shock-absorbing system. Only under extreme operating temperatures or severe shock or vibration should the compact disc player skip or mute. If the customer travels an abnormally rough road, a skip condition may be normal. Test drive the vehicle on a normal road with a known good CD. If the condition is still present, replace the radio.

The use of CD lens cleaner discs is not advised, due to the risk of contaminating the lens of the CD optics with lubricants internal to the CD mechanism.

Single Disc Loading
To operate the ICDX in the single play mode, press and release the LOAD button. An audible beep is heard and "WAIT" is displayed, followed by "INSERT CD". The LED to the right of the disc door turns green and remains illuminated for at least 10 seconds. Load a disc when the LED turns green. If the radio is on, the disc will begin to play automatically. To load a CD with the ignition OFF, press the CD eject button to enable the 25 second load interval.

Multi Disc Loading
To operate the ICDX in the multi disc mode, press and hold the LOAD button for 4 seconds. An audible double beep is heard and "WAIT" is displayed, followed by "MULTI LOAD". The LED to the right of the disc door begins to flash. The radio will also display the message "INSERT CD 1-6". When the LED stops flashing and turns green, load a disc. Once the disc is loaded the LED begins to flash again. The radio again displays the message "MULTI LOAD" to indicate the multi load mode is still active. When the LED stops flashing and turns green, load another disc. Repeat this procedure to continue loading discs. The CD changer holds up to six discs.

When the changer is full (six discs are loaded) and the LOAD button is pressed, three audible beeps are heard and the message "CHANGER FULL" is displayed.

Removing CDs
Use the CD eject button to remove a disc or discs. If the CD is not removed within 10 seconds the ICDX will auto reload the CD and resume playback.

Perform the following to eject:
- To remove the current CD, press and release the CD eject button. An audible beep is heard and the LED flashes red. The message "REMOVE CD 1-6" is displayed.
- To remove multiple discs, press and release the CD eject button for 4 seconds. An audible double beep is heard and the LED to the right of the disc door begins to flash indicating a disc is being ejected. "EJECT ALL" is displayed followed by "REMOVE CD 1-6" until all CDs are ejected.

IMPORTANT:: Pressing the CD button repeatedly, causes the radio receiver's 25 second eject timer to reset at each press of the button. This will cause the receiver to not eject a disc until the 25 second time period has elapsed.

Selecting CDs
Use the preset buttons 1-6 to select the CD to be played.

Song List Feature
The ICDX has a feature called Song List. This feature is capable of saving 20 track selections to a play list.

To save tracks into Song List, perform the following :
1. The disc player must be on with at least one disc loaded.
2. The message "S-LIST" should not be displayed on the radio. If "S-LIST" is present, press the SONG LIST button to turn it off.
3. Select the desired disc by pressing the numbered pushbutton and then use the SEEK right arrow button to locate the track that you want to save. The track will begin to play.
4. Press and hold the SONG LIST button for two or more seconds to save the track into memory. When SONG LIST is pressed an audible beep is heard. After two seconds of pressing SONG LIST continually, two audible beeps will sound to confirm that the track has been saved.
5. Repeat steps 3 and 4 for saving other selections.

To play the Song List press the SONG LIST button. One beep is heard and "S-LIST" appears on the display. The recorded tracks will begin to play in the order that they were saved.

To delete tracks from the Song List.
1. The disc player must be on.
2. Press the SONG LIST button. The message "S-LIST" appears on the display.
3. Press the SEEK button to locate desired track to be deleted.
4. Press and hold the SONG LIST button for two seconds. After two seconds, two beeps are heard confirming that the track has been deleted.

To delete the entire Song List.
1. The disc player must be on.
2. Press the SONG LIST button. The message "S-LIST" appears on display.
3. Press the SEEK button to locate desired track to be deleted.
4. Press and hold the SONG LIST button for more than four seconds. After two seconds, a beep will be heard followed by two beeps and a final beep after four seconds. The message "S-LIST EMPTY" appears on the display.