Cellular System, Entertainment System, and Navigation System: Diagnosis Chevrolet Silverado 2500 HD

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Diagnostic Starting Point - Cellular, Entertainment, and Navigation

Begin the system diagnosis with the Diagnostic System Check - Vehicle . The Diagnostic System Check - Vehicle will provide the following information

1. The identification of the control modules which command the system
2. The ability of the control modules to communicate through the serial data circuit
3. The identification of any stored DTCs and their status

The use of the Diagnostic System Check - Vehicle will identify the correct procedure for diagnosing the system and where the procedure is located.

Scan Tool Output Controls

Amplifier (Bose)

Radio

Rear HVAC/RSA Module

Vehicle Communication Interface Module (VCIM)

Scan Tool Data List

Amplifier (Bose)

Vehicle Communication Interface Module (VCIM)

Digital Radio Receiver

Rear HVAC/RSA

Radio

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

Conditions for Running the DTC

The radio is in ACCESSORY, RUN, or RAP power mode.

Conditions for Setting the DTC

The DTC will set for one or more of the following conditions.

1. Vehicle speed from serial data is more than 5 km/h (3 mph) and vehicle speed pulse from the EBCM is 0 km/h (0 mph).
2. Vehicle speed calculated from the navigation processing software is more than 36 km/h (22 mph) and vehicle speed pulse from the EBCM is 0 km/h (0 mph) for 10 seconds continuously.

Conditions for Clearing the DTC

1. The condition must be corrected.
2. A history DTC clears after 100 malfunction-free ignition cycles.

Circuit/System Testing

1. Ignition OFF, disconnect the EBCM harness connector and X4 radio harness connector.
2. Test for less than 1 volt between the EBCM harness connector appropriate terminal and radio harness connector X4 terminal 5. Terminal 28 (10 Series without JL4) Terminal 14 (20/30 Series without JL4) Terminal 11 (10 Series With JL4) Terminal 32 (20/30 Series With JL4) If greater than specified value repair short to voltage.
3. Test for infinite resistance between the radio harness connector X4 terminal 5 and ground. If less than specified value repair short to ground.
4. Test for less than 1 ohm between the EBCM harness connector appropriate terminal and radio harness connector X4 terminal 5. If greater than specified value repair open circuit.
5. If all circuits test normal, replace the EBCM.

Circuit Description

This DTC is set as current in all vehicle communication interface module (VCIM) service parts and has been implemented as a reminder to contact the OnStar® Call Center to properly update the customer's account once the new module has been installed. This call is initiated automatically after the installation of the replacement VCIM, and the completion of the Setup New VCIM procedure on the scan tool. No external circuits are involved.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC B1001 Option Configuration Error

The DTC is only run once per ignition cycle after a VCIM service part installation.

This DTC is set as current in every VCIM service part, until the Setup New VCIM procedure on the scan tool has been performed after a service replacement.

Action Taken When the DTC Sets

1. The OnStar® status LED turns red.
2. The blue OnStar® Call Center button is disabled.

A current DTC clears following the successful completion of the Setup New VCIM procedure via the scan tool.

DTC B1001

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

The following are conditions that must be present in order for the radio to enable the diagnostics.

1. The radio is in ACCESSORY, RUN, or RAP power mode.
2. The system voltage is at least 9 volts and no more than 16 volts.

Amplifier senses an over-heat condition higher than 95°C (203°F) of the internal circuitry.

Amplifier mutes all speaker channels.

1. The condition must be corrected.
2. A history DTC clears after 100 malfunction-free ignition cycles.
3. The amplifier receives the clear code command from the scan tool.

Extended use of extremely high volume, especially in warm weather conditions, may induce this DTC. Under these conditions it may be normal for this DTC to set to prevent permanent damage to the amplifier circuitry. If DTC persists without excessive volume, replace the amplifier.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

Diagnostic Fault Information

DTC B1025-B1095

The radio is ON.

The radio sets a current status for this DTC when a short to ground, short to voltage or an open is detected on any of the 6 speaker channel outputs from the radio.

No sound is present from one or more of the speakers.

The fault condition is not present for 0.25 second.

Diagnostic Aids

Speakers located in the front A-pillar are connected to the same channel as the speaker in the door. A DTC will only set after the amplifier only on up-level radios.

DTC Set In Amplifier

1. With the scan tool, verify the DTC is set by the amplifier.
2. Ignition OFF, disconnect the suspect speaker. Test for 1-50 ohms across the speaker terminals. If not within the specified range specified range replace the suspect speaker.
3. Disconnect the suspect audio amplifier harness connector.
4. Test for less than 1 volt on both of the suspect speaker output circuits. If greater than 1 volt repair short to voltage.
5. Test for infinite resistance between both of the suspect speaker output circuits and ground. If resistance is less than specified value, repair short to ground.
6. Test for less than 1 ohm between suspect speaker output circuits amplifier harness connector and the suspect speaker harness connector. If greater than specified value repair open or high resistance.

1. If all circuits test normal, replace the amplifier.

DTC Set In Radio With Amplifier

1. With the scan tool, verify the DTC is set by the radio.
2. Disconnect the suspect audio amplifier harness connector.
3. Disconnect the radio harness connector.
4. Test for less than 1 volt on both of the suspect low level audio signal circuits. If greater than 1 volt repair short to voltage.
5. Test for infinite resistance between both low level audio signal circuits and ground. If less than specified value, repair short to ground.
6. Test for less than 1 ohm between the suspect low level audio signal circuits amplifier harness connector and the suspect speaker harness connector. If greater than specified value repair open or high resistance.

1. If all circuits test normal, replace the amplifier.

DTC Set In Radio Without Amplifier

1. With the scan tool, verify the DTC is set by the radio.
2. Ignition OFF, disconnect the suspect speaker. Test for 1-50 ohms across the suspect speaker terminals. If not within the specified range specified range replace the suspect speaker.
3. Disconnect the suspect radio harness connector.
4. Test for less than 1 volt on both of the low level audio signal circuits. If greater than 1 volt repair short to voltage.
5. Test for infinite resistance between both of the suspect low level audio signal circuits and ground. If resistance is less than specified value, repair short to ground.
6. Test for less than 1 ohm between the suspect speaker harness connector both low level audio signal circuits and the suspect radio harness connector. If greater than specified value repair open or high resistance.

1. If all circuits test normal, replace the radio.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

This test is run every 300 milliseconds.

The DRR detects an antenna fault.

The radio displays "No XM Signal" or "Check Antenna".

1. The condition must be corrected.
2. The DTC clears after 100 malfunction-free ignition cycles.

1. Ignition OFF, disconnect the antenna coax from the DRR. Connect the test antenna to the DRR.
2. Turn the ignition ON, radio ON tuned to XM. Verify that DTC B1259 is not current. If the DTC B1259 is still current, replace the DRR.
3. Ignition OFF, disconnect the DRR antenna from the coaxial cable. Test the resistance of the antenna coaxial cable center conductor from end to end. Verify the resistance is less than 5 ohms. If the resistance is greater than 5 ohms, replace the antenna coaxial cable.
4. Test the resistance of the antenna coaxial cable outer shield from end to end. Verify the resistance is less than 5 ohms. If the resistance is greater than 5 ohms, replace the antenna coaxial cable.
5. Test the resistance of the antenna coaxial cable between the center conductor and the outer conductor. Verify there is infinite resistance between both conductors. If there is less than infinite resistance between the inner conductor and the outer conductor of the coaxial cable, replace the antenna coaxial cable. If the coaxial cable tests normal, replace the digital radio antenna.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

DTC B1287

The following are conditions that must be present in order for the radio to enable the diagnostics.

1. The radio is in ACCESSORY, RUN, or RAP power mode.
2. The system voltage is at least 9 volts and no more than 16 volts.

The radio detects a fault on the Amp Control circuit 400 ms after radio activates the Remote Enable circuit.

Radio sets the DTC and continues to output correct state.

1. The condition must be corrected.
2. A history DTC clears after 100 malfunction-free ignition cycles.
3. The radio receives the clear code command from the scan tool.

Ignition OFF, test the amplifier control and remote enable signal circuits for an open, a short to voltage, or a short to ground.

1. If the circuit tests normal, replace the radio.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

DTC B1288

The following are conditions that must be present in order for the radio to enable the diagnostics.

1. The radio is in ACCESSORY, RUN, or RAP power mode.
2. The system voltage is at least 9 volts and no more than 16 volts.

Circuit failure 400 ms after radio activates Remote Enable.

Radio sets the DTC and defaults the video display to Normal mode.

1. The condition must be corrected.
2. A history DTC clears after 100 malfunction-free ignition cycles.
3. The radio receives the clear code command from the scan tool.

1. Ignition OFF, disconnect the harness connector of the rear video display. Ignition ON, with a DMM verify there is 100 to 300 Hz on the video display mode control signal circuit. If 100 to 300 Hz is not present on the video display mode signal circuit test for an open, a short to voltage, or a short to ground. If the video display mode signal circuit tests normal, replace the radio.
2. If 100 to 300 Hz is present and the video display mode signal circuit tests normal, replace the rear video display.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

DTC B1289

The following are conditions that must be present in order for the radio to enable the diagnostics.

1. The radio is in ACCESSORY, RUN, or RAP power mode.
2. The system voltage is at least 9 volts and no more than 16 volts.

Circuit failure 400 ms after radio activates Remote Enable.

Radio sets the DTC and defaults the video display to Full Brightness mode.

1. The condition must be corrected.
2. A history DTC clears after 100 malfunction-free ignition cycles.
3. The radio receives the clear code command from the scan tool.

1. Ignition OFF, disconnect the harness connector of the rear video display. Ignition ON, with a DMM verify there is 100 to 300 Hz on the video display brightness control signal circuit. If 100 to 300 Hz is not present on the video display brightness control signal circuit test for an open, a short to voltage, or a short to ground. If the video display brightness control signal circuit tests normal, replace the radio.
2. If 100 to 300 Hz is present and the video display brightness control signal circuit tests normal, replace the rear video display.

The vehicle communication interface module (VCIM) detects that the cellular microphone is connected through the cellular microphone signal circuit and the cellular microphone low reference circuit.

This diagnostic procedure supports the following DTC

DTC B2455 Cellular Phone Microphone Circuit Malfunction

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 10 seconds.

1. The VCIM detects an open in the cellular microphone low reference circuit or a short to voltage in the cellular microphone signal circuit.
2. The above conditions are present for greater than 10 seconds.

1. The VCIM will not receive any signal from the microphone.
2. Calls can be placed but the caller cannot be heard.
3. The OnStar® status LED turns RED.

1. The VCIM detects the microphone connected for 5 consecutive 100 millisecond cycles.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The VCIM receives the clear DTC command from the scan tool.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

The global positioning system (GPS) antenna is connected to the navigation radio by a coaxial cable.

The radio must detect one of the following power modes

1. ACC
2. ON
3. RAP
4. RAP UNLK

1. The navigation radio test the GPS antenna every 10 seconds.
2. The radio determines there is an open in the GPS antenna.

1. Unable to get GPS location updated, the radio uses the last reported position and the vehicle speed signal to calculate the vehicle position.
2. Route guidance may be inaccurate.
3. This failure has no effect outside the navigation system.

1. A current DTC clears when the radio does not detect the failure for more than 10 seconds.
2. A history DTC clears after 50 ignition cycles with no repeat of the failure.

1. Turn ON the ignition. Disconnect the GPS coaxial cable from the GPS antenna. Verify there is 4-5.5 volts between the center conductor and the shield of the coaxial cable. If 4-5.5 volts are present, replace the GPS antenna.
2. Turn the ignition OFF. Disconnect the GPS coaxial cable from the radio. Test the resistance of the GPS coaxial cable center conductor from end to end. Verify the resistance is less than 5 ohms. If the resistance greater than 5 ohms, replace the GPS coaxial cable.
3. Test the resistance of the GPS coaxial cable between the center conductor and the outer conductor. Verify there is infinite resistance between both conductors. If there is less than infinite resistance between the inner conductor and the outer conductor of the GPS coaxial cable, replace the GPS coaxial cable. If the GPS coaxial cable tests normal, replace the radio.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 1 second.

1. The VCIM does not detect the presence of a cellular antenna.
2. The above conditions are present for greater than 1 second.

1. The vehicle is unable to connect to the OnStar® Call Center.
2. The OnStar® status LED turns red.

1. The VCIM detects the presence of a cellular antenna.
2. A history DTC clears after 50 malfunction-free ignition cycles.
3. The VCIM receives the clear DTC command from the scan tool.

Component Testing

1. Disconnect the cellular antenna coax connector at the VCIM.
2. Test for infinite resistance between the center conductor and the outer metal shield of the cellular antenna coax cable. If meter does not read infinite, replace the cellular antenna coax cable.
3. Test for less than 1 ohm of resistance at the cellular antenna coax connector from end to end. If greater than specified value, replace the cellular antenna coax cable.
4. If coax cable tests normal, test or replace the VCIM.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

The internal backlighting of the navigation display screen located in the navigation radio.

The radio must detect one of the following power modes

1. ACC
2. ON
3. RAP
4. RAP UNLK

1. The navigation radio test the navigation display backlighting antenna every 1 second.
2. The radio determines there is a malfunction or overheat condition in the navigation display backlighting.

The navigation backlight may be too bright, dim or blank.

1. A current DTC goes to history when the radio does not detect the failure for more than 1 second.
2. A history DTC clears after 50 ignition cycles with no repeat of the failure.

Occasionally it is possible to overheat the navigation display backlighting due to excessive ambient heat inside the vehicle. In this instance it may be necessary to allow time for the display to cool.

1. Allow the navigation display to cool if the ambient temperature inside the vehicle is excessive and the radio is hot to the touch. Verify the navigation display is cool and the DTC has cleared and gone to history. If the DTC has gone to history and the navigation display backlighting operates normal clear the DTC and go to Diagnostic Aids.
2. Observe the brightness of the navigation display backlighting. Verify the backlighting can be adjusted or the screen is not blank. If the display backlighting is malfunctioning or the DTC will not clear, replace the radio.

The OnStar® button assembly consists of 3 buttons, Call/Answer, OnStar® Call Center, and OnStar® Emergency. Ten volts are supplied to the button assembly on the keypad supply voltage circuit. Each of the buttons, when pressed, complete the circuit across a resister allowing a specific voltage to be returned to the vehicle communication interface module (VCIM) on the keypad signal circuit. Depending upon the voltage range returned, the VCIM is able to identify which button has been pressed.

This diagnostic procedure supports the following DTC

DTC B2476 Cellular Phone Select Service Switch Malfunction (3 button assembly)

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 300 milliseconds.

1. The VCIM powers the button assembly through the keypad supply voltage circuit for 11.5 milliseconds, turns the power off, then waits for 50 milliseconds and sees a voltage value greater than 1.8 volts on this circuit.
2. The above conditions are present for greater than 300 milliseconds.

1. The VCIM will ignore all inputs from the OnStar® button assembly.
2. No calls can be placed.
3. The OnStar® status LED turns RED.

1. The VCIM powers the button assembly through the keypad supply voltage circuit for 11.5 milliseconds, turns the power off, then waits for 50 milliseconds and sees a voltage value less than 1.8 volts on this circuit.
2. A history DTC clears after 50 malfunction-free ignition cycles.
3. The VCIM receives the clear DTC command from the scan tool.

The OnStar® button assembly consists of 3 buttons, Call/Answer, OnStar® Call Center, and OnStar® Emergency. Ten volts are supplied to the button assembly on the keypad supply voltage circuit. Each of the buttons, when pressed, complete the circuit across a resister allowing a specific voltage to be returned to the vehicle communication interface module (VCIM) on the keypad signal circuit. Depending upon the voltage range returned, the VCIM is able to identify which button has been pressed.

This diagnostic procedure supports the following DTC

DTC B2482 Cellular Phone Select Switch Range/Performance

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 15 seconds.

1. A button is pressed or stuck for more than 15 seconds.
2. The above conditions are present for greater than 15 seconds.

1. The VCIM will ignore all inputs from the OnStar® button assembly.
2. No calls can be placed.
3. The OnStar® status LED turns RED.

1. The button will be declared unstuck after a 50 milliseconds normal cycle.
2. A history DTC clears after 50 malfunction-free ignition cycles.
3. The VCIM receives the clear DTC command from the scan tool.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 1 second.

1. The VCIM does not detect a navigation signal.
2. The above conditions are present for greater than 1 second.

1. The OnStar® Call Center cannot locate the vehicle.
2. The OnStar® status LED turns red.

1. The VCIM detects the presence of a navigation antenna.
2. A history DTC clears after 50 malfunction-free ignition cycles.
3. The VCIM receives the clear DTC command from the scan tool.

1. Disconnect the navigation antenna coax connector from the navigation antenna.
2. Test for infinite resistance between the center conductor of the coax to the metal outer shield. If not specified value, replace the navigation antenna coax.
3. Test for less than 1 ohm resistance of navigation antenna coax connector from end to end. If not specified value, replace the navigation antenna coax.
4. If cellular antenna coax tests normal, test or replace the VCIM.

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the system. Refer to «Checking Aftermarket Accessories»(ref-278019-S10639375482008012100000) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «OnStar One or More Buttons Inoperative»(ref-277998-S13275035702008012100000)
2. «OnStar Call Center Remote Function Requests Inoperative»(ref-277998-S11430046102008012100000)
3. «Unable to Contact OnStar Call Center»(ref-277998-S21160013842008012100000)
4. «OnStar Microphone Inoperative - Caller Cannot Be Heard»(ref-277998-S20751303382008012100000)
5. «OnStar Voice Recognition Inoperative»(ref-277998-S12662809892008012100000)
6. «OnStar Steering Wheel Control Functions Inoperative»(ref-277998-S27335790212008012100000)
7. «OnStar Button LED Inoperative»(ref-277998-S41360834402008012100000)
8. «No (or Noisy) OnStar Audio»(ref-277998-S23360745402008012100000)
9. «OnStar Global Positioning System (GPS) Data Not Current or Inaccurate»(ref-277998-S40943226592008012100000)

Symptoms - Entertainment

1. Inspect for aftermarket devices which could affect the operation of the Radio/Audio system. Refer to «Checking Aftermarket Accessories»(ref-278019-S10639375482008012100000) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Radio Poor Reception»(ref-277998-S06520033202008012100000)
2. «Audio Distortion - One or More Speakers»(ref-277998-S23180025862008012100000)
3. «Radio Displays LOC, LOCKED, or CODE»(ref-277998-S12409436882008012100000)
4. «Radio Displays CAL or CAL ERR»(ref-277998-S33958423772008012100000)
5. «Reduced Volume - One or More Speakers»(ref-277998-S37171432422008012100000)
6. «Noise Compensated Volume Inoperative»(ref-277998-S42065248552008012100000)
7. «Speakers Inoperative - One or More (With Amplifier)»(ref-277998-S37586259272008012100000) or «Speakers Inoperative - One or More (Without Amplifier)»(ref-277998-S11409065712008012100000)
8. «Video Entertainment System Inoperative»(ref-277998-S42253435852008012100000)
9. «Video Display is Poor or Blank»(ref-277998-S12303787142008012100000)
10. «Radio Audio Inoperative at Rear Seat Audio (RSA) Control»(ref-277998-S41677166712008012100000)
11. «Radio Controls Inoperative - Rear Seat»(ref-277998-S08464314232008012100000)

Audio System Troubleshooting Hints

Many conditions that affect radio operation may be corrected without removing the radio from the car. Verify the condition, and follow the diagnostic procedures in order to isolate and correct the condition. In order to properly diagnose any audio system problems, ensure that you have a fully charged battery.

Preliminary Inspections

1. Check for any aftermarket equipment that may have been installed on the vehicle. If aftermarket equipment is found disconnect it and check if the audio noise is still present. Inspect that the antenna connector and the antenna coaxial cable are clean and tight.
2. For reception concerns, first determine if the customer is within the listening area of the stations they are attempting to receive.
3. Stations at the lower end of the FM band are more susceptible to audio noises than stations at the higher end.
4. If the noise is only from one speaker check for the following before speaker replacement: Isolate the noise using the J 39916-A CD and Cassette Diagnostic Audio Kit. See «Special Tools»(ref-277998-S10218936542008012100000) . Inspect the speaker connections to ensure they are clean and tight. Refer to «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000) . Inspect for a loose or incorrectly installed speaker or surrounding trim. Loose trim can cause a buzz or flutter which sounds like a malfunctioning speaker.
5. Ignition noise on the FM band may be an indication of an ignition system problem.
6. Inspect that all vehicle grounds are clean, tight and free of corrosion.
7. Inspect the rear defogger grid lines for large breaks or dark spots.
8. Inspect the connections at the radio antenna module to ensure that they are clean and tight.
9. Compare the customers vehicle to another of similar model and audio system to determine if the condition is abnormal.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. Turn ON the ignition, with the engine OFF and turn ON the radio. Adjust the fade and balance controls to mid range and Insert the CD from the J 39916-A to identify the suspect speaker. See «Special Tools»(ref-277998-S10218936542008012100000) .
2. Test for a short to B+ or short to ground on the suspected speaker circuits between the amplifier and the suspect speaker. If all circuits test normal, replace suspect speaker if distortion is found.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

Digital Radio Poor or No Reception

1. Ignition OFF, disconnect the digital radio receiver antenna coax. Connect the test antenna to the digital radio receiver.
2. Turn the ignition ON, radio ON tuned to XM. Is the reception improved? If the reception is not improved, replace the DRR.
3. Ignition Off. Disconnect the DRR antenna from the coaxial cable. Test the resistance of the antenna coaxial cable center conductor from end to end. Verify the resistance is less than 5 ohms. If the resistance is greater than 5 ohms, replace the antenna coaxial cable.
4. Test the resistance of the antenna coaxial cable outer shield from end to end. Verify the resistance is less than 5 ohms. If the resistance is greater than 5 ohms, replace the antenna coaxial cable.
5. Test the resistance of the antenna coaxial cable between the center conductor and the outer conductor. Verify there is infinite resistance between both conductors. If there is less than infinite resistance between the inner conductor and the outer conductor of the coaxial cable, replace the antenna coaxial cable. If the coaxial cable tests normal, replace the digital radio antenna.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. The GPS signal title on the scan tool will display a Yes or No dependant upon whether or not the module sees an increment of the seconds transmitted by GPS signals to the vehicle communication interface module. Upon entering this screen, the GPS signal title will automatically display Yes, regardless of the presence of time increment, for at least 2 seconds, while the algorithm in the scan tool determines the status of the clock. If increment is found, Yes is continually displayed. If the clock remains static, No is displayed. The scan tool looks for increment every second, regardless of current display.
2. Inaccurate or aged GPS position concerns which are no longer present may have been due to the temporary loss of GPS signal reception by the vehicle. Conditions such as driving through tunnels or parking structures while making an OnStar® keypress will restrict the navigation antenna from a clear view of the satellites in the sky and may have caused this temporary data loss.

1. Disconnect the navigation antenna coax cable from the navigation antenna within the wiring harness.
2. Disconnect the navigation antenna from the VCIM.
3. Test for infinite resistance between the center conductor of the coax to the metal outer shield. If it does not read infinite, replace the navigation antenna coax cable.
4. Test for greater than 1 ohm resistance at the navigation antenna coax center conductor from end to end. If less than specified value, replace the navigation antenna assembly.

1. If greater specified value, replace the navigation antenna coax cable.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. Ignition OFF, disconnect the harness connector at the cellular microphone.
2. Ignition ON, test for greater than 9 volts between the signal circuit terminal B and ground. If less than specified value, test the cellular microphone signal circuit for a short to ground, open/high resistance. If the circuit tests normal, replace the VCIM.
3. Test for greater than 9 volts between the cellular microphone signal circuit terminal B and the drain circuit terminal A. If less than specified value, test the drain wire for an open/high resistance. If the circuit tests normal, replace the VCIM.
4. If all circuit test normal, test or replace the cellular microphone assembly.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. Verify the OnStar® voice recognition is operating normally. If the OnStar® voice recognition is inoperative, refer to «OnStar Microphone Inoperative - Caller Cannot Be Heard»(ref-277998-S20751303382008012100000) .
2. Ignition OFF, disconnect the radio harness connector X1 and VCIM harness connector X3.
3. Test for less than 1 volt on the voice recognition audio signal circuit radio harness connector terminal 4 and ground. If greater than specified value, repair short to voltage.
4. Test for greater than 1 ohm between the voice recognition audio signal circuit radio harness connector terminal 4 and ground. If less than specified value, repair short to ground.
5. Test for less than 1 ohm between the voice recognition audio signal circuit radio harness connector terminal 4 and the voice recognition audio signal circuit VCIM harness connector terminal 2.
6. If greater than specified value, repair open circuit.
7. Test for less than 1 volt on the voice recognition audio low reference circuit radio harness connector terminal 5 and ground. If greater than specified value, repair short to voltage.
8. Test for greater than 1 ohm between the voice recognition audio low reference circuit radio harness connector terminal 5 and ground. If less than specified value, repair short to ground.
9. Test for less than 1 ohm between the voice recognition audio low reference circuit radio harness connector terminal 5 and the voice recognition audio low reference signal circuit VCIM harness connector terminal 4. If greater than specified value, repair open circuit.
10. If all circuits test normal, replace the radio.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. Remove the GPS antenna and cable and place it outside the vehicle. Verify the GPS reception is operational within 5 minutes. If GPS becomes operational, remove any suspect window tint or objects that may obstruct the GPS signal.
2. Replace the GPS antenna. Verify the GPS reception is operational within 5 minutes. If GPS is not operational, replace the radio.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. Turn the ignition ON. Disconnect the noise compensation microphone.
2. Measure for 7-9 volts between the noise compensation microphone supply circuit and the drain circuit. If the voltage is in between 7-9 volts, replace the noise compensation microphone.

1. If the voltage is greater than 9 volts or less than 7 volts and a open, short to ground, or short to voltage can not be found, replace the radio.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

The customer concern may have been due to a lack of cellular service in a given area. A failure in the National Cellular Network infrastructure that has since been corrected.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. The customer concern may have been due to a lack of cellular service in a given area or a failure in the National Cellular Network infrastructure that has since been corrected.
2. If the prompt OnStar Request Ended is heard without pressing the white dot button at the end of an OnStar® keypress, the OnStar® system at one time made a successful cellular connection, but was unable to complete the call. If repeated calls are placed with this result, contact the General Motors Technical Assistance Center.
3. An inaccurate or aged GPS position may have been due to the temporary loss of GPS signal reception by the vehicle in instances, such as driving through tunnels or parking structures which restrict the navigation antenna from a clear view of the satellites in the sky.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. Center the balance and fade adjustment on the radio. If adjustment of the fade and balance eliminates the concern, review the operation of the radio with the customer.
2. Verify that the wireless headphones are set to the proper channel and are working properly. If the wireless headphones are not operating properly, refer to «Video Entertainment System Wireless Headphone Inoperative»(ref-277998-S11150052592008012100000) .
3. Ignition OFF, disconnect the X1 RSA connecter harness.
4. Verify that a test lamp illuminates between the B+ circuit terminal 5 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
5. Verify that a test lamp illuminates between the ground circuit terminal 6 and B+. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
6. If all circuits test normal, replace the RSA control module.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. Test or repair open, short to ground or short to voltage on the rear seat audio (RSA) ground circuit and battery positive voltage circuit. If all circuits test normal, replace the RSA control module.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

Program the radio.

1. If the radio still displays CAL ERR, replace the radio.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

Program the radio.

1. If the radio still locked, replace the radio.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

Without Amplifier

1. Center the balance and fade adjustment on the radio. If adjustment of the fade and balance eliminates the concern, review the operation of the radio with the customer.
2. Turn ON the radio and tune the radio to a channel with no reception (static).
3. Record the AC voltage of the suspect speaker channel and compare and verify the AC voltage output of the suspect low level audio signal is the same as the opposite low level channel. If the suspect speaker channel low level audio signal AC voltage is lower than other channels, replace the radio.

1. If the recorded AC voltage is the same level as other speaker low level audio signal AC outputs, replace the suspect speaker.

With Amplifier

1. Center the balance and fade adjustment on the radio. If adjustment of the fade and balance eliminates the concern, review the operation of the radio with the customer.
2. Disconnect the harness connector containing the suspect low level audio circuits at the amplifier.
3. Ignition ON and radio ON, tune the radio to a channel with no reception (static).
4. Record the AC voltage of the suspect low level audio signal circuits. Compare and verify the AC voltage output of the suspect low level audio signal is the same as opposite low level channel. If the suspect speaker channel low level audio signal AC voltage is lower than other channels, replace the radio.
5. Reconnect the harness connector containing the low level audio circuits and disconnect the harness connector at the individual speaker.
6. Record the AC voltage of the suspect low level audio signal circuits. Compare and verify the AC voltage output of the suspect speaker signal is similar to other low level audio signal circuits. If the suspect channel speaker signal AC voltage is lower than other channels, replace the amplifier.

1. If the recorded AC voltage is the same level as other speaker signal AC outputs, replace the suspect speaker.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

Circuit/System Testing (Without Amplifier)

1. Ignition OFF, disconnect the left front speaker harness connector.
2. Test for AC voltage between the left front low level audio signal (+) and left front low level audio signal (-). If AC voltage is not present, replace the radio.

Circuit/System Testing (With Amplifier Except UQA+Y91)

1. Ignition OFF, disconnect the C3 harness connector.
2. Turn the Ignition ON and radio ON.
3. At the amplifier C3 harness connector, test for AC voltage between the left front low level audio signal (+) and left front low level audio signal (-). If AC voltage is not present, replace the radio.
4. Disconnect the C1 amplifier harness connector.
5. Connect a test lamp between the B+ circuit connector terminal 4 and ground. Verify the test lamp illuminates. If the test lamp does not illuminate, repair open/high resistance.
6. Connect a test lamp between the ground circuit connector terminal 8 and B+. Verify the test lamp illuminates. If the test lamp does not illuminate, repair open/high resistance.
7. Ignition ON and radio ON, test for greater than 9 volts on the remote enable signal circuit connector terminal 8. If less than specified value repair open/high resistance or replace the radio.
8. If all circuits test normal, replace the amplifier.

Circuit/System Testing (With UQA+Y91 Amplifier)

1. Ignition OFF, disconnect the C3 harness connector.
2. Turn the Ignition ON and radio ON.
3. At the amplifier C3 harness connector, test for AC voltage between the left front low level audio signal (+) and left front low level audio signal (-). If AC voltage is not present, replace the radio.
4. Disconnect the C1 amplifier harness connector.
5. Connect a test lamp between the B+ circuit connector terminal 4 and ground. Verify the test lamp illuminates. If the test lamp does not illuminate, repair open/high resistance.
6. Connect a test lamp between the ground circuit connector terminal 8 and B+. Verify the test lamp illuminates.
7. If all circuits test normal, replace the amplifier.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. Center the balance and fade adjustment on the radio. If adjustment of the fade and balance eliminates the concern, review the operation of the radio with the customer.
2. Ignition OFF, disconnect the amplifier harness connector containing the suspect low level audio circuits.
3. Ignition ON, operate the radio and increase the radio volume.
4. At the suspect amplifier harness connector, verify AC voltage is present between the suspect low level audio signal (+) and suspect low level audio signal (-) circuits. If AC voltage is not present, repair open circuit or replace the radio.
5. Reconnect the amplifier harness connector.
6. Disconnect the suspect speaker harness connector.
7. Verify AC voltage is present between the suspect speaker output (+) and speaker output (-) circuits. If AC voltage is not present, repair open speaker output circuit or replace the suspect speaker.
8. If all circuits test normal, replace the amplifier.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. Center the balance and fade adjustment on the radio. If adjustment of the fade and balance eliminates the concern, review the operation of the radio with the customer.
2. Ignition OFF, Disconnect the suspect speaker harness connector.
3. Ignition ON, operate the radio and increase the volume.
4. Verify AC voltage is present between the suspect speaker (+) and speaker (-) circuits. If AC voltage is present, replace the speaker. If AC voltage is not present repair open/high resistance.
5. If all circuits test normal replace the radio.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. The customer concern may have been due to a lack of cellular service in a given area. A failure in the National Cellular Network infrastructure at the time of the customers failed connection that has since been repaired may also have been the cause.
2. If an OnStar® emergency call is able to successfully connect the vehicle to the OnStar® Call Center when an OnStar® Call Center button press is not, there may be a failure in the ability of the OnStar® system in the vehicle to be recognized by the local cellular carrier.
3. If the prompt "OnStar® request ended" is heard, without pressing the white dot button at the end of the OnStar® keypress, the OnStar® system at one time has made a successful cellular connection, but was unable to complete the call. If repeated calls are placed with this result, contact General Motors Technical Assistance Center.

1. Verify that there is no exterior damage to the cellular antenna. If damaged, test or replace the cellular antenna assembly.
2. Disconnect the cellular antenna coax from the VCIM.
3. Disconnect the cellular antenna coax from the cellular antenna.
4. Test for infinite resistance between the center conductor of the coax and the outer metal shield. If different than specified value, replace the cellular antenna coax.
5. Test for less than 1 ohm resistance at the cellular antenna coax center conductor from end to end. If greater than specified value, replace the cellular antenna coax cable.
6. Use the scan tool to access the STID, ESN and Transceiver I.D. and contact the General Motors Technical Assistance Center.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

Flip open the rear video display. With the ignition ON, operate the rear entertainment system using several known good DVD disks. Observe the rear video screen.

1. If the screen turns ON but is blank, test for an open, short to ground and short to power on the DVD video signal circuits to the rear video display. If the DVD video signal circuits test normal, replace the video display.

1. If the video screen is still malfunctioning, replace the radio.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. Disconnect the rear video display harness connector. With the ignition ON, operate the rear entertainment system. Verify there is voltage on the remote enable signal circuit. If voltage is not present on the remote enable signal circuit, test and repair open or short to ground. If the enable signal circuit tests normal but there is no voltage, replace the radio.
2. Test and repair open, short to ground and short to power on the ground and battery positive voltage circuits at the rear video display. If the video display power and ground circuits test normal, replace the rear video display.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

1. Verify the system works with a known good remote. If the known good remote operates properly, replace the suspect remote.
2. Operate the radio and turn ON the rear seat audio (RSA). Verify the remote headphones operate normally. If the remote headphones do not operate properly, refer to «Video Entertainment System Wireless Headphone Inoperative»(ref-277998-S11150052592008012100000) .
3. Install a scan tool. Monitor the button presses in the radio data display. Verify the radio responds to the remote when the buttons are pressed. If the radio does not respond, test the remote infra-red signal circuits for an open, short to ground or short to B+. If the infra-red signal circuits test normal replace audio system transceiver module.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

No Audio From Wireless Headphones

1. Turn ON the wireless headphones. Verify the power indicator lamp on the wireless headphone illuminates. If the power indicator lamp does not illuminate on the wireless headphones check or replace the wireless headphone batteries. If the batteries are OK replace the wireless headphones.
2. Activate the RSA. Set both wireless headphones to the proper channel to hear RSA. Adjust the volume up on both wireless headphones. Verify that only one set of wireless headphones operate properly. If only one set of wireless headphones do not have audio, replace the suspect wireless headphone set.
3. With a DMM, verify there is B+ at the infra-red module supply voltage circuit when the RSA is activated. If B+ is not present, test for a open or short to power on the infra-red module supply voltage circuit. If the infra-red module supply voltage circuit tests normal, replace the rear seat audio control module.
4. At the infra-red module connector harness, test for AC voltage between the low reference circuit and the left and right infra-red audio signal circuits. Verify there is AC voltage with the RSA activated. If AC voltage is not present, test for an open, short to ground or short to B+ on the low reference and both left and right infra-red audio signal circuits. If the low reference and audio signals test normal replace the rear seat audio control module.
5. Ignition OFF, disconnect the harness connector of the infra-red module. Test for less than 1.0 ohm of resistance between the ground circuit terminal 12 and ground. If greater than the specified range, repair the ground circuit.

1. If the ground circuit tests normal, replace the infra-red module.

Audio In One Channel of the Wireless Headphones or Distortion

1. Activate the RSA. Set both wireless headphones to the proper channel to hear RSA. Adjust the volume up on both wireless headphones. Verify that only one set of wireless headphones operates properly. If only one set of wireless headphones is faulty, replace the suspect wireless headphone set.
2. At the infra-red module connector harness, test for AC voltage between the low reference circuit and the left and right infra-red audio signal circuits. Verify there is AC voltage with the RSA activated. If AC voltage is not present, test for an open, short to ground or short to B+ on the low reference and both left and right infra-red audio signal circuits. If the low reference and audio signals test normal replace the rear HVAC control module.
3. Test for an open, short to ground or short to B+ on the low reference and both left and right infra-red audio signal circuits. If the low reference and audio signals test normal replace the infra-red module.

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-278018-S03493196652008012100000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-278018-S38264170562008012100000) provides an overview of each diagnostic category.

OnStar® Cellular, GPS, and Diagnostic Limitations

The proper operation of the OnStar® System is dependent on several elements outside the components integrated into the vehicle. These include the National Cellular Network Infrastructure, the cellular telephone carriers within the network, and the global positioning system (GPS).

The cellular operation of the OnStar® system may be inhibited by factors such as the user's range from an analog or digital cellular tower, the state of the cellular carriers' equipment, and the location where the call is placed. Making an OnStar® keypress in areas that lack sufficient cellular coverage or have a temporary equipment failure will result in either the inability of a call to complete with a data transfer or the complete inability to connect to the OnStar® Call Center. The OnStar® system may also experience connection issues if the identification numbers for the module, station identification number (STID) and electronic serial number (ESN), are not recognized by the cellular carriers local signal receiving towers. OnStar® cellular connection issues such as these require the assistance of the General Motors Technical Assistance Center OnStar® Group, which coordinates with cellular carriers to resolve connection issues.

The satellites that orbit earth providing the OnStar system with GPS data have almost no failures associated with them. In the event of a no GPS concern, the failure will likely lie with the inability of the system to gain GPS signals because of its location, i.e. in a parking structure, hardware failure, or being mistaken with an OnStar® call which has reached the Call Center without vehicle data.

During diagnostic testing of the OnStar® system, the technician should ensure the vehicle is located in an area that has a clear unobstructed view of the open sky, and preferably, an area where analog or digital cellular calls have been successfully placed. These areas can be found by successfully making an OnStar® keypress in a known good OnStar® equipped vehicle and confirming success with the OnStar® Call Center advisor. Such places can be used as a permanent reference for future OnStar® testing.