GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

Entertainment/Communication Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Special Tools Required

J 39916-A CD Diagnostic Audio Kit

Circuit/System Testing (Digital Radio One or More Speakers Inoperative)

  1. Ignition OFF, disconnect the radio C2 harness connector.
  2. Ignition ON, operate the digital radio and increase the radio volume.
  3. Verify AC voltage is not present between the suspect remote radio audio signal (+) and remote radio audio signal (-).
  4. If AC voltage is present, replace the radio.
  5. Ignition OFF, disconnect the digital radio harness connector.
  6. Test for less than 1 volt on both suspect remote radio audio signal (+) and remote radio audio signal (-).
  7. If greater than 1 volt repair short to voltage.
  8. Test for less than 1 ohm between the suspect remote radio audio signal (+) radio harness connector terminal and the suspect remote radio audio signal (+) digital radio C2 harness connector terminal.
  9. If greater than specified value repair open or high resistance.
  10. Test for less than 1 ohm between the suspect remote radio audio signal (-) radio harness connector terminal and the suspect remote radio audio signal (-) digital radio C2 harness connector terminal.
  11. If greater than specified value repair open or high resistance.
  12. If all circuits test normal, replace the digital radio receiver (DRR).

Circuit/System Testing (One or More Speakers Inoperative With Amplifier)

  1. Center the balance and fade adjustment on the radio.
  2. If adjustment of the fade and balance eliminates the concern, review the operation of the radio with the customer.
  3. Ignition OFF, Disconnect the suspect amplifier harness connector. If the suspect speaker inputs are contained in the same harness as the amplifier power and ground It will be required to re-connect the power and ground by using a fused jumper harness.
  4. Ignition ON, operate the radio and increase the radio volume.
  5. Verify AC voltage is not present between the suspect speaker output (+) and speaker output (-) circuits.
  6. If AC voltage is present, replace the radio.
  7. Reconnect the amplifier harness connector.
  8. Disconnect the suspect speaker harness connector.
  9. Verify AC voltage is not present between the suspect speaker output (+) and speaker output (-) circuits.
  10. If AC voltage is present, replace the suspect speaker.
  11. Ignition OFF, Disconnect the suspect amplifier harness connector
  12. Test for less than 1 volt on both suspect speaker output (+) and speaker output (-) circuits.
  13. If greater than 1 volt repair short to voltage.
  14. Test for less than 1 ohm between the suspect speaker output (+) radio harness connector terminal and the suspect speaker output (+) speaker harness connector terminal.
  15. If greater than specified value repair open or high resistance.
  16. Test for less than 1 ohm between the suspect speaker output (-) radio harness connector terminal and the suspect speaker output (-) speaker harness connector terminal.
  17. If greater than specified value repair open or high resistance.
  18. If all circuits test normal, replace the amplifier.

Circuit/System Testing (All Speakers Inoperative With Amplifier)

  1. Ignition OFF, Disconnect the C1 amplifier harness connector.
  2. Connect a test lamp between the B+ circuit connector terminal 8 and ground. Verify the test lamp illuminates.
  3. If the test lamp does not illuminate, repair open/high resistance.
  4. Connect a test lamp between the ground circuit connector terminal 5 and B+. Verify the test lamp illuminates.
  5. If the test lamp does not illuminate, repair short to voltage or open/high resistance.
  6. Ignition ON and radio ON, test for greater than 9 volts on the amplifier enable signal circuit connector terminal 8.
  7. If less than specified value repair open/high resistance or replace the radio.
  8. If all circuits test normal, replace the amplifier.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Module References for radio, amplifier, and DDR programming and setup
    •  Speaker Replacement Reference