GM Service Manual Online
For 1990-2009 cars only

Schematic Reference: Radio/Navigation System Schematics .

Diagnostic System Check - Entertainment System

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

Speaker(s) - Reduced Volume/Audio 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 .

With RPO UW4 and UZ6

    • Speaker output circuit high resistance or shorted to ground--Test the speaker output circuits for high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs .
    • Defective speaker--Replace the appropriate speaker. Refer to Radio Front Side Door Lower Speaker Replacement , Front Upper Speaker Replacement , or Radio Rear Speaker Replacement .

Important: The following procedure assumes all speakers are operative for all modes of operation except digital radio.

With RPO U2K

    • Audio common circuit open--Test the audio common circuit for an open. Refer to Circuit Testing and Wiring Repairs .
    • Speaker output circuit high resistance or shorted to ground--Test the speaker output circuits for high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs .
    • No audio output from the digital radio receiver--Replace the digital radio receiver. Refer to Digital Radio Receiver Replacement and Digital Radio Receiver Setup .
    • No digital radio audio output from the radio--Replace the radio. Refer to Radio Replacement .