GM Service Manual Online
For 1990-2009 cars only

Schematic Reference: Radio/Audio System Schematics

Preliminary Information

Perform the Diagnostic System Check - Vehicle in Vehicle DTC Information.

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.

All Speakers Inoperative

Important: The following information lists the most probable cause of the concern to the least probable cause followed by the appropriate test for that condition. If the list leads to the replacement of a component, always inspect for a poor connection before proceeding with the replacement. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

With RPO UM8

  1. Battery positive voltage circuit to the amplifier open--Test the battery positive voltage circuit to the amplifier for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Ground circuit to the amplifier open--Test the ground circuit to the amplifier for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  3. Speaker output from the radio shorted--Test each speaker output of the radio for a short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  4. No audio output from the amplifier--Replace the amplifier. Refer to Radio Speaker Amplifier Replacement in Entertainment.

One Speaker Inoperative

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 Circuit Testing and Wiring Repairs in Wiring Systems.

Without RPO UM8

  1. Speaker output circuit from amplifier open--Test the appropriate speaker output circuits for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Important: The radio must be programmed after replacement. Refer to Service Programming System (SPS) in Programming and Setup.

  3. No audio output from the radio--Test for any AC voltage between the appropriate speaker output circuits at the speaker harness connector, disconnected with the radio volume adjusted to 50 percent. If AC voltage is present, replace the speaker. Refer to Speaker Replacement Reference . If no AC voltage is present, replace the radio. Refer to Control Module References in Computer/Integrating Systems.
  4. No audio output from the amplifier--Test for any AC voltage between the appropriate speaker output circuits at the speaker harness connector, disconnected with the radio volume adjusted to 50 percent. If AC voltage is present, replace the speaker. Refer to Speaker Replacement Reference . If no AC voltage is present, replace the amplifier. Refer to Radio Speaker Amplifier Replacement in Entertainment.

Speakers - One Channel Inoperative

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 Circuit Testing and Wiring Repairs in Wiring Systems.

  1. Speaker output circuit from amplifier shorted--Test the appropriate speaker output circuits for a short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Replace the amplifier. Refer to Control Module References in Computer/Integrating Systems.