GM Service Manual Online
For 1990-2009 cars only

Schematic Reference: Radio/Audio System Schematics

Connector End View 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 in Vehicle DTC Information.

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 Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

With RPO UQ2

  1. Speaker output shorted--Test all speaker outputs for a short. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Defective radio--Replace radio. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

With RPO U85

  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. Amplifier control circuit to the amplifier open or shorted to ground--Test amplifier control circuit for an open or short to ground. 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 left front 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 Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
  4. No audio output from the amplifier--Replace the amplifier. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

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

With RPO U2K or U2L

  1. Remote radio audio signal circuit shorted--Test the remote radio audio signal circuits for a short. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. No audio output from the digital radio receiver--Replace the digital radio receiver. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
  3. No digital radio audio output from the radio--Replace the radio. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.