GM Service Manual Online
For 1990-2009 cars only

Schematic Reference: Radio/Audio System Schematics

Diagnostic System Check - Entertainment System

Always perform the Entertainment System Diagnostic System Check before proceeding with these diagnostic procedures. Refer to Diagnostic System Check - Radio/Audio System .

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 U79

  1. Speaker output open. Test the appropriate speaker output circuits for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. 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 Radio Replacement .

With RPO UQ3

  1. Speaker output circuit from amplifier open or shorted. Test the appropriate speaker output circuits for an open or short. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Low level audio circuit open. Test the appropriate low level audio circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  3. No low level audio output from the radio. Test for any AC voltage between the appropriate low level audio signal circuits at the amplifier harness connector, disconnected with the radio volume adjusted to 50 percent. If no AC voltage is present, replace the radio. Refer to Radio Replacement .
  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 .