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

Description and Operation

Radio/Audio System Description and Operation

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

Without 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. Turn ON the radio and tune the radio to a channel with no reception (static).
  4. 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.
  5. If the suspect speaker channel low level audio signal AC voltage is lower than other channels, replace the radio.
    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.
  2. If adjustment of the fade and balance eliminates the concern, review the operation of the radio with the customer.
  3. Disconnect the harness connector containing the suspect low level audio circuits at the amplifier.
  4. Ignition ON and radio ON, tune the radio to a channel with no reception (static).
  5. 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.
  6. If the suspect speaker channel low level audio signal AC voltage is lower than other channels, replace the radio.
  7. Reconnect the harness connector containing the low level audio circuits and disconnect the harness connector at the individual speaker.
  8. 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.
  9. If the suspect channel speaker signal AC voltage is lower than other channels, replace the amplifier.
    If the recorded AC voltage is the same level as other speaker signal AC outputs, replace the suspect speaker.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Module References for amplifier and radio replacement
    •  Speaker Replacement Reference