GM Service Manual Online
For 1990-2009 cars only

Schematic Reference: Radio/Audio System Schematics

Connector End Views Reference: Entertainment Connector End Views

Diagnostic System Check - Vehicle

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

Speakers - Distortion

Important: The following information lists the most probable cause of the concern to the least probable cause. If the list leads to the replacement of a component, always inspect for a poor connection before proceeding with replacement. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

  1. Low level audio circuit open--Test the appropriate low level audio circuit for an open. Refer to Circuit Testing and Wiring Repairs .
  2. Defective speaker--Replace the appropriate speaker. Refer to Speaker Replacement Reference .

With RPO U2K

Audio output signal circuit from digital radio receiver open. Test left, right, and audio common signal circuits for opens. Refer to Circuit Testing and Wiring Repairs .