Entertainment System: Other Hummer H2 I

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Identifying Concerns

1. In order to isolate the source of the noise/poor reception, identify the ignition switch position that the concern is most noticeable: Turn the ignition switch to the accessory position. Turn ON the radio. Seek up 88-108 FM then 550-1600 AM. Record the number of valid radio stations where the tuner stops. Repeat these steps with the ignition ON, and the engine OFF then again with the engine running.
2. Return the ignition switch to the position that the concern was most noticeable.
3. Remove fuses or circuit breakers one at a time until the noise has been eliminated.
4. Identify what systems or components are powered by the fuse.
5. Reinstall all fuses and circuit breakers.
6. Disconnect the components powered by the fuse one at a time until the concern has been eliminated.

Corrective Action

1. Inspect the ground integrity of the component or system causing the noise.
2. Malfunctioning and marginal components such as relays and solenoids may cause noise and/or poor reception.
3. Always use a braided ground strap when applying additional grounds and keep the ground strap as short as possible.
4. If the noise source is found to be coming from the vehicle harness: Route the antenna cable separately from the wire harness that is emitting the noise. Use aluminum or nickel tape in order to shield the antenna cable. Try variations of the following repairs: Try adding only aluminum or nickel tape before adding a ground strap to the tape. Wrap a ground strap 360 degrees around the tape, securing the other end of the strap to chassis ground.
5. Capacitors work best on switch pops and low frequency noise.
6. Filters work best on high frequency whines and static.
7. After adding any suppression device, inspect all of the vehicle systems including those not related to the audio system, for proper operation and function.
8. Whenever possible, make a test harness that includes filters or capacitors. Always inspect the effectiveness and operation before permanent installation.
9. If an audible pop is caused due to operating a switch, perform the following repairs as necessary: Add a capacitor across the contacts of the switch. Add a capacitor from the battery positive voltage (B+) side of the switch to chassis ground. Add a capacitor from the ground side of the switch to chassis ground.
10. Use the following available noise suppression devices: 220 micro farad (50 V) capacitor GM P/N 1227895 - Works well for ignition system related noise. 0.47 micro farad capacitor GM P/N 1227894 - Works well for switches and relays. Feed through capacitor GM P/N 477371 - Works well for high current situations. Filter package GM P/N 1224205 - Works well for low current situations. Fuel pump suppressor GM P/N 25027405 21 inch braided ground strap GM P/N 8910791 19 inch braided ground strap GM P/N 6286800 10.5 inch braided ground strap GM P/N 6287160 8.5 inch braided ground strap GM P/N 12091511

Generator Whine Concerns

1. Inspect the ground terminal and cable for high resistance.
2. Inspect the generator and brackets for loose or coated mounting bolts.
3. Inspect that the ground straps between the engine and the frame are clean and tight.
4. If the noise is still present, inspect the charging system for proper operation. Refer to «Diagnostic Starting Point - Engine Electrical»(ref-187208-S37352758532005083100000) in Engine Electrical.
5. Install a filter GM P/N 1224205 in the battery voltage feed circuit to the radio.
6. If the noise is not eliminated, install the filter in each following variation: Install the filter with the single wire side toward the radio and the ground wire attached to chassis ground. Remove the ground to the filter. Reverse the filter so the 2-wire side is toward the radio with the ground wire attached to chassis ground. Remove the ground from the filter.
7. If the filter GM P/N 1224205 causes a delay when turning the radio ON or OFF, or other problems, remove the filter and install a 0.47 micro farad capacitor to chassis ground.
8. Before reassembling the vehicle, remove any unneeded filters.
9. Test the functionality all of the vehicle systems including those not related to the audio system, for proper operation and function.

Radio Poor Reception

Schematic Reference: Radio/Audio System Schematics (non Class 2 Amplifier) or Radio/Audio System Schematics (Class 2 Amplifier)

Always perform the Radio/Audio System Diagnostic System Check before proceeding with these diagnostic procedures. Refer to Diagnostic System Check - Entertainment System .

Antenna Checking Procedures

Perform the following tests for the type of antenna on the vehicle.

Mast Antennas

Unplug antenna lead-in connector from radio receiver and plug a test antenna into radio. Make sure antenna base is grounded to the vehicle chassis and keep hands off the mast.

Check radio reception in an area away from electrical interferences. Tune to several weak and strong AM and FM stations. If the radio reception improved, the problem exists with the antenna and/or lead-in cable. If the reception is still poor, refer to Audio System Troubleshooting Hints .

Scheme 19

Radio Poor Reception

Refer to the table when testing the antenna and/or lead-in cable.

1. Measure the resistance from the coax center conductor to antenna mast.
2. Total resistance from end to end of center conductor: RG-58/RG-59 type cable - less than 0.20 ohms RG-62/RG-62M type cable - less than 3.5 ohms
3. When checking the resistance, cautiously wiggle the lead-in tip and cable. Refer to «Testing for Intermittent Conditions and Poor Connections»(ref-187209-S18750056402005083100000) in Wiring Systems.
4. Measure the resistance from the cable center conductor to metal case.
5. Replace the antenna and/or lead-in cable when the above readings are not obtained.

Some vehicles come equipped with a pre-amplified AM/FM antenna that is powered by SW 12+. If the antenna loses this power source or a ground, poor reception can occur. To see if your vehicle is equipped with a pre-amplified antenna refer to Radio/Audio System Schematics (non Class 2 Amplifier) or Radio/Audio System Schematics (Class 2 Amplifier) .

Audio Distortion - One or More Speakers

Audio Distortion - One or More Speakers

Radio Displays LOC, LOCKED, or CODE

Radio Displays LOC, LOCKED, or CODE

Radio Displays CLN or CLEAN

Radio Displays CLN or CLEAN

Radio Displays CAL or CAL ERR

Radio Displays CAL or CAL ERR

Speed Compensated Volume

Speed Compensated Volume

Tape Player Weak, Slow, or Garbled Output

Tape Player Weak, Slow, or Garbled Output

Steering Wheel Controls Inoperative

Steering Wheel Controls Inoperative

Reduced Volume - One or More Speakers

Schematic Reference: Radio/Audio System Schematics (non Class 2 Amplifier) or Radio/Audio System Schematics (Class 2 Amplifier)

Connector End Views Reference: Entertainment Connector End Views

Always perform the Entertainment System Diagnostic System Check before proceeding with these diagnostic procedures. Refer to Diagnostic System Check - Entertainment System .

Speakers - Reduced Volume

1. Speaker output circuit high resistance. Test the appropriate speaker output circuits for high resistance. Refer to «Circuit Testing»(ref-187209-S36455577572005083100000) and «Wiring Repairs»(ref-187209-S11567408862005083100000) in Wiring Systems.
2. Low level audio circuit open. Test the appropriate low level audio circuit for an open. Refer to «Circuit Testing»(ref-187209-S36455577572005083100000) and «Wiring Repairs»(ref-187209-S11567408862005083100000) in Wiring Systems.
3. Defective speaker - Replace the appropriate speaker. Refer to «Speaker Replacement Reference»(ref-187213-S32010060852005083100000) .

Speakers Inoperative - One or More

Schematic Reference: Radio/Audio System Schematics (non Class 2 Amplifier) or Radio/Audio System Schematics (Class 2 Amplifier)

Preliminary Information

Perform the Diagnostic System Check - Entertainment System .

All Speakers Inoperative

With RPO UM8

1. Battery positive voltage circuit to the amplifier open. Test the battery positive voltage circuit to the amplifier for an open. Refer to «Circuit Testing»(ref-187209-S36455577572005083100000) and «Wiring Repairs»(ref-187209-S11567408862005083100000) in Wiring Systems.
2. Ground circuit to the amplifier open. Test the ground circuit to the amplifier for an open. Refer to «Circuit Testing»(ref-187209-S36455577572005083100000) and «Wiring Repairs»(ref-187209-S11567408862005083100000) in Wiring Systems.
3. Speaker output from the radio shorted. Test each speaker output of the radio for a short to ground or short to voltage. Refer to «Circuit Testing»(ref-187209-S36455577572005083100000) and «Wiring Repairs»(ref-187209-S11567408862005083100000) in Wiring Systems.
4. No audio output from the amplifier. Replace the amplifier. Refer to «Amplifier Replacement»(ref-187213-S37272706462005083100000) .

One Speaker Inoperative

Without RPO UM8

1. Speaker output circuit from amplifier open. Test the appropriate speaker output circuits for an open. Refer to «Circuit Testing»(ref-187209-S36455577572005083100000) and «Wiring Repairs»(ref-187209-S11567408862005083100000) in Wiring Systems.
2. No audio output from the radio. Test for any AC voltage between the appropriate speaker output circuits at the speaker harness connector, disconnected with the radio volume adjusted to 50 percent. If AC voltage is present, replace the speaker. Refer to «Speaker Replacement Reference»(ref-187213-S32010060852005083100000) . If no AC voltage is present, replace the radio. Refer to «Radio Replacement»(ref-187213-S16083092362005083100000) .
3. No audio output from the amplifier. Test for any AC voltage between the appropriate speaker output circuits at the speaker harness connector, disconnected with the radio volume adjusted to 50 percent. If AC voltage is present, replace the speaker. Refer to «Speaker Replacement Reference»(ref-187213-S32010060852005083100000) . If no AC voltage is present, replace the amplifier. Refer to «Amplifier Replacement»(ref-187213-S37272706462005083100000) .

Speakers - One Channel Inoperative

1. Speaker output circuit from amplifier shorted. Test the appropriate speaker output circuits for a short to ground or short to voltage. Refer to «Circuit Testing»(ref-187209-S36455577572005083100000) and «Wiring Repairs»(ref-187209-S11567408862005083100000) in Wiring Systems.
2. Replace the amplifier. Refer to «Amplifier Replacement»(ref-187213-S37272706462005083100000) .

Radio Audio Inoperative at Rear Seat Audio (RSA) Control

Radio Audio Inoperative at Rear Seat Audio (RSA) Control

Radio Setup (With RPO UM8)

The following service procedure requires programming or setup procedures to be performed on the radio.

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

1. The power output (wattage) of the broadcasting station
2. The location of the vehicle (or receiver) relative to the broadcast tower.
3. Obstacles between the tower and the receiver
4. Atmospheric conditions
5. What band (AM or FM) the station is broadcasting
6. Type of antenna and the ground plane

AM Reception

The AM band has a lower frequency range than the FM band. These longer wavelengths

1. Bend around Obstacles
2. Follow the curvature of the earth
3. 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. 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

1. Reflect off obstacles
2. Are absorbed by the ground
3. 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

1. Height of the broadcast antenna
2. Height of the receiving antenna
3. Terrain and buildings in the broadcast path

Audio Amplifier

The radio supplies low level audio signals to the audio amplifier in order to boost the signal sent to the speakers. The class 2 signal circuit allows the radio to recognize that an amplifier is present. Once the radio detects an audio amplifier, it will output low level audio signals. The audio amplifier is turned on when it receives a message via the class 2 serial data circuit indicating that the radio is on. The audio amplifier can also be a Non-Class 2 Bose amp, which was a mid year change in 2004 MY. Ensure which amplifier is installed in the vehicle.

Auto Volume Control and Speed Compensated Volume

Auto volume control is available with the Class 2 audio amplifiers. This utilizes a noise compensation microphone the provides the amplifier with a sample of the ambient noise within the vehicle. If the noise level is high the amplifier will adjust the volume accordingly.

Speed compensated volume uses the vehicle speed provided to the amplifier, to adjust the volume, to compensate for the increase in road and wind noise associated with increased speed. This option is only available with the Non-Class 2 Bose Amplifier.

Theft Deterrent

The 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

1. A radio is installed from another vehicle
2. 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 in this section to diagnose the "Theftlock" DTC for further information.

Integral Multi Disc CD Changer (IMDX)

The Integral Multi Disc CD Changer has the capability of storing and playing up to six (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.

To operate the Integral Multi Disc CD Changer in the single play mode, depress the LOAD button for less than 2 seconds, an audible beep can then be heard. When the disc door opens the LED to the right of the disc door will first turn red then green to indicate the CD can be loaded. The radio will also display the message INSERT CD 1 and the changer will pull the disc into the play position. To operate the changer in the multi disc mode, depress the MODE button for more than two seconds and the LED to the right of the disc door will first turn red then green to indicate CDs can be loaded. The radio will also display the message MULTI LOAD to indicate the multi load mode has been initiated and the changer will begin accepting a disc for however many empty slots there may be. If eight seconds elapse before the next disc is loaded, the multi load mode is cancelled and can be re-initiated if desired by depressing the load button again for more than two seconds. If the changer is full, (6 discs are loaded) the single play and multi load modes cannot be executed. When this occurs, three audible beeps are heard and the message CHANGER FULL is displayed.

Remote Playback Device

The remote playback device is either installed at the factory or in some instances it is dealer installed. There are three types of remote playback devices, a multi disc remote CD changer, a single disc CD player and a cassette player. All three 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 CD's 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 11/2 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. NOTICE: 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. 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 CD's, the CD symbol will flash on the display until the changer is ready to play.

Radio Data System (RDS)

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 sub-carrier. A sub-carrier 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

1. RDS functions are provided in the FM broadcast band only.
2. RDS functions will only work with FM broadcast stations that are broadcasting RDS data.
3. Not all FM Broadcast stations broadcast RDS data or offer all of the RDS services.
4. RDS functions may not work properly when reception is weak, reception is of poor quality, or RDS is not implemented properly by the FM Broadcaster.

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

1. The name of the station.
2. The type of program.
3. General information such as artist and song title, call in phone numbers, etc.

RDS is always on. When tuned to a non-RDS station, your radio will display frequency information as you would normally expect. When tuned to a RDS station, your radio will change from displaying the frequency of the FM station to displaying the call letters of the station or display the nickname of the station. This feature is known as the Program Service Name.

Controlling the Radio

RDS can control the radio when data the receiver can use responds to timely information performing the following

1. Interrupt the playback of your cassette or CD for traffic or emergency bulletins.
2. Search for stations by type of program.
3. Automatically follow network programming from transmitter to transmitter as you travel from one listening area to another.
4. Set your clock to the time that the RDS Broadcast station broadcasts.

Viewing and Selecting RDS Information for Display

Press the TUNE SELECT PUSH RCL knob once for less then 2 seconds when the radio displays the program service 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 name will be displayed (if the broadcaster is broadcasting one). The program type 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 program type name is more desirable to display when tuned to an RDS station than the Program Service Name, press the TUNE SELECT PUSH RCL 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 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 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 in 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.

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

1. Press and hold the AM/FM button for two seconds or more.
2. The radio will display AF ON or AF OFF depending on the current condition of AF and a confirmation beep will be heard.

When AF is enabled and you recall a 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 broadcast once a minute. To set the clock using RDS clock data perform the following

1. Press and hold the HR and MIN buttons together for two or more seconds to update the time.
2. The display will show UPDATED after receiving the broadcast time data.
3. If the broadcaster is not broadcasting the time data, the radio will display NO UPDATE and the time remains unchanged.

Radio Error Messages

The radio displays the following error messages

Voice Recorder

To record a message, press the button with the circle on it and begin speaking. Press the button with the circle on it again to stop recording. System allows you to record up to 4 minutes of messaging.

You may also press and hold the button with the circle on it while you are speaking and then let it go when you are finished.

To play back messages, press the button with the right arrow on it. Pressing the right arrow button more than once will return you to previously recorded messages. If you press and hold this button for more than one second, all of the recorded messages will be played back.

To delete messages, press the button with the square on it while the message is playing. If you press and hold the right arrow button and the circle button at the same time for 1/2 second, all of the messages will be deleted.

Rear Seat Audio (RSA)

The Rear Seat Audio and Rear HVAC control functions in the GMT 360/370/800 programs are combined into one dual function control unit. The audio portion of the controller provides dual audio source capability from the vehicle audio system.

When in use, the audio portion of the controller enables rear seat occupants to listen to a different music source than the front seat occupants. The audio volume at each headphone is independently controlled by the rear passengers. A VF display in the center of the controller provides graphic communication to the rear seat operator the state of various rear audio functions. The dual source mode functionality is an embedded feature of the compatible radio receiver. Primary radio controls always have control of the front speaker outputs. Primary radio mode control is not affected by the operation of the rear audio control and always has priority over the rear audio control.

The front seat occupants have the capability to override and disable the rear audio controller operation through the primary radio controls. An ignition cycle also causes the rear audio to default to the OFF state.

Even when the primary radio is powered OFF, shutting OFF all speakers in the vehicle, the RSA controller functions are available. The rear passengers can still listen to any available audio source through the headphones.

The controller shall have two stereo volume controls to vary the audio volume to the headphones. For each headphone, one element will provide the variable load to the left audio output and the other element will provide the variable load to the right audio output.

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 satellite 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 rebroadcast them at much higher power levels in order to ensure reception in areas with densely packed tall buildings. 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 communicates with the digital radio receiver via the class 2 communications circuit. The digital radio receiver sends low level audio signals to the audio amplifier.

Amplifier

The amplifier in early build vehicles is a class 2 device that communicates with the scan tool on the Class 2 bus. The Class 2 amplifier will set a U100 in the radio if there is a communication problem. The late build vehicles have a NON-Class 2 amplifier that does not communicate over the Class 2 bus and therefore the NON-Class 2 amplifier will not set codes. Both amplifiers have similar operating characteristics, therefore, there are not separate diagnostics for the NON-Class 2 amplifier.