Part 1
Radio/Audio System Description and Operation (Part 1)
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 on some vehicle lines a rear seat audio (RSA) unit.
The uplevel system differs from the base level system by providing enhanced audio system features. These features may include the radio data system (RDS), two additional speakers, rear seat audio (RSA), and DVD video entertainment system. 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:
* Base Radio (U1C)-AM/FM Stereo with CD
* Uplevel Radio (UN0)-AM/FM Stereo, CD, Auto Tone, and RDS
* Uplevel Radio (UP0)-AM/FM Stereo, Cassette, CD, and RDS
* Uplevel Radio (UC6)-AM/FM, Integral 6 Disc CD Changer (ICDX), and RDS
Speaker System
There are two speaker systems available on this vehicle and consist of the following components:
Base UW4 System
4 Speaker System
* Two 6 inch extended range speakers (ERS) mounted in both front doors.
* Two 6 x 9 extended range speakers (ERS) mounted to the rear shelf (sedan only).
* Two 6 inch extended range speakers (ERS) mounted in both rear doors (extended sedan only).
Premium UZ6 System
6 Speaker System
* Two 6 inch high sensitivity speakers (HSS) mounted in both front doors.
* Two 6 x 9 extended range speakers (ERS) mounted to the rear shelf (sedan only).
* Two 6 inch extended range speakers (ERS) mounted in both rear doors (extended sedan only).
* Two tweeter speakers mounted in the upper door trim on both front doors.
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 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.
Cassette Automatic Music Search (AMS)
Previous AMS
Pressing and releasing the SEEK SCAN DOWN button within 2 seconds enters the previous selection AMS mode.
The radio will seek at a faster then normal playing speed to the beginning of the current cassette selection or to the previous selection.
Pressing the SEEK SCAN DOWN button within 2 seconds a number of times will seek back a number of selections equal to the number of button presses. Pressing the SEEK SCAN UP button will reduce the number of selections the radio will seek back to.
Next AMS
Pressing and releasing the SEEK SCAN UP button within 2 seconds enters the next selection AMS mode.
The radio will seek at a faster then normal playing speed to the beginning of the next cassette selection.
Pressing the SEEK SCAN UP button within 2 seconds a number of times will seek forward a number of selections equal to the number of button presses. Pressing the SEEK SCAN DOWN button will reduce the number of selections the radio will seek back to.
Cut Tape Bypass
The Cut Tape Bypass feature detects when a cassette tape breaks or becomes too tight to play. When this is detected the tape will stop playing and eject.
To activate the Cut Tape Bypass feature follow these steps:
1. The radio must be OFF and in one of the following modes.
* Retained accessory power (RAP)
* RUN power mode
* ACCESSORY power mode
2. Press and hold the SOURCE button for 2 seconds. After 2 seconds the TAPE ICON appears and begins to flash for 5 seconds. The text READY is displayed and the TAPE ICON will flash.
The feature is now active.
3. The Cut Tape Bypass will remain On until the accessory is ejected.
Without the activation of the Cut Tape Bypass feature accessories, like scrubbing type tape head cleaners and CD adapter kits (which have no internal tape for the radio to sense), will be ejected.
Clean Cassette Player
The radio provides a feature that alerts the user when the tape player requires cleaning. The radio still plays tapes when cleaning is required. The tape player should be cleaned as soon as possible to prevent damage to the tapes and player.
The radio provides a tape clean timer (50 hours typical). When the tape clean timer expires, the radio displays CLEAN TAPE for 5 seconds whenever the radio enters the tape mode. Use a non-abrasive cleaning cassette to clean the tape player.
After cleaning the tape player, reset the tape clean timer by pressing and holding the EJECT button for 2 seconds. The radio displays TAPE CLEANED.
Each item in the list below represents topics covered in detail below.
* AM/FM Reception
* Antenna System
* Theft Deterrent
* Integral 6 Disc CD Changer (ICDX)
* Rear Seat Audio (RSA)
* Rear Seat Entertainment Control
* Radio Data System (RDS)
* Steering Wheel Audio Controls
* XM Satellite Radio
* XM Advisory Messages
* Radio Circuit Operation
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:
* 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
* 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 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:
* 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
Antenna System
The radio receiver uses an antenna to receive transmitted radio signals from a radio broadcast station. After the radio signal is received by the radio, it undergoes further processing by the radio tuner.
There are two types of antenna systems available on this vehicle. The antenna system (RPO U77) on the sedan model is comprised of a very thin metal grid which is permanently affixed to the rear glass. A radio antenna module connects to the antenna via a coax cable. On the extended model a fixed mast antenna (RPO U71) is used.
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 vehicle ID (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:
* A radio is installed from another vehicle.
* A module which communicates on the GMLAN 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. 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.
Integral 6 Disc CD Changer (ICDX [Uplevel])
The Integral Multi Disc CD Changer has the capability of storing and playing up to 6 compact discs. The Integral Multi Disc CD Changer 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.
Important: The CD mechanism within the ICDX radio will begin an initialization routine after a battery connect (e.g., connecting radio connector C1). The initialization process takes approximately 25 seconds to complete. It is very critical that the initialization is completed before removing battery power from the radio, in order for the complex moving parts of the CD mechanism to be positioned properly before shipping and/or handling purposes. Damage may result to the moving parts of the CD mechanism if battery power is removed during the initialization routine. The damage occurs to the CD mechanism during subsequent shipping or handling operations. The extent of the damage causes the CD mechanism not to recover and the mechanism becomes inoperative.
Single Disc Loading
To operate the Integral Multi Disc CD Changer in the single play mode, press and release the LOAD button within 2 seconds. The radio display indicates to wait before inserting a CD. The CD mechanism will move the lowest numbered empty slot into position and then produce an audible beep. Load a disc when the radio display indicates to insert a CD. If the radio is ON, the disc will begin to play automatically. If the radio is OFF, press the LOAD button for the disc to play.
Multi Disc Loading
To operate the Multi Disc CD Changer in the multi disc mode, press and hold the LOAD button for more than two seconds. An audible beep will be heard and the radio displays the message ALL CDs then an indication to wait before inserting a CD. The CD mechanism will move the lowest numbered empty slot into position and then produce an audible beep. The radio will then display a message to insert a CD. After inserting a CD the radio produces an audible beep. The radio displays another message indicating to wait before inserting a CD. Insert another CD when the display indicates inserting one. Repeat this procedure to continue loading the remaining 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.
To play one of the CD's, press one of the preset buttons.
Removing CDs
Use the eject button, the button labeled CD to remove a disc or discs.
Perform the following to eject:
* To remove a single disc, press and release the EJECT button within 2 seconds. The message REMOVE CD is displayed.
Important:: Pressing the CD button repeatedly, causes the radio receivers 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.
* To remove multiple discs, press and release the EJECT button for more than 2 seconds. An audible beep is heard and the radio displays a message indicating a disc is being ejected. The message REMOVE CD is displayed. After removing the CD, the CD mechanism moves into place to eject the next CD. This process is repeated until the last CD is removed.
Song List Feature
The Multi Disc CD Changer 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 push-button 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 2 or more seconds to save the track into memory. When SONG LIST is pressed an audible beep is heard. After 2 seconds of pressing SONG LIST continually, 2 audible beeps will sound to confirm that the track has been saved. The message TRACK ADDED is displayed.
5. Repeat steps 3 and 4 for saving other selections.
6. The radio displays SONG LIST FULL when the song list contains 20 songs.
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 2 seconds. One beep is heard immediately followed by 2 beeps confirming that the track has been deleted. The message TRACK DELETE is displayed for 5 seconds.
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 and hold the SONG LIST button for more than 4 seconds. One beep is heard immediately followed by 2 beeps. Then another 2 beeps are heard signifying the song list is deleted. The message SONG LIST EMPTY appears on the display for 5 seconds.
When a CD is ejected, the CD track selections saved for the CD are deleted from the song list.