GM Service Manual Online
For 1990-2009 cars only

Schematic Reference: Radio/Audio System Schematics

Speakers - Reduced Volume

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 in Wiring Systems.

With RPO U62

  1. Speaker output circuit high resistance. Test the appropriate speaker output circuits for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Defective speaker - Replace the appropriate speaker. Refer to Speaker Replacement Reference .

With RPO UQ3

  1. Speaker output circuit high resistance. Test the appropriate speaker output circuits from the audio amplifier for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Defective speaker - Replace the appropriate speaker. Refer to Speaker Replacement Reference .

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

With RPO U2K or U2L

  1. Audio common circuit open. Test the audio common circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Audio left or right circuit open. Audio common circuit open. Test the audio common circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.