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

Component Connector End Views

Electrical Information Reference

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

Important:  Noise compensated volume only available on vehicles equipped with Y91 or UQS.

  1. Turn the ignition ON. Disconnect the noise compensation microphone.
  2. Measure for 7-9 volts between the noise compensation microphone supply circuit terminal A and the drain circuit terminal B.
  3. If the voltage is less than the specified range, test the circuits for a short to ground, or an open/high resistance. If the circuit tests normal, replace the auido amplifier.
    If the voltage is greater than the specified range, test the circuits for a short to voltage. If the circuit tests normal, replace the audio amplifier.
  4. If all circuits test normal, replace the noise compensation microphone.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for radio replacement, setup, and programming