For 1990-2009 cars

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 .

### 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 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 Radio Replacement .

#### 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 Radio Replacement .
4. No audio output from the amplifier. Replace the amplifier. Refer to Radio Speaker Amplifier Replacement .

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

#### With RPO UQ2

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 an audible level. If AC voltage is present, replace the speaker. Refer to Radio Rear Speaker Replacement , Radio Front Side Door Lower Speaker Replacement , or Front Upper Speaker Replacement . If no AC voltage is present, replace the radio. Refer to Radio Replacement .

#### With RPO U85

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 an audible level. If AC voltage is present, replace the speaker. Refer to Radio Rear Speaker Replacement , Radio Front Side Door Lower Speaker Replacement , or Front Upper Speaker Replacement . If no AC voltage is present, replace the amplifier. Refer to Radio Speaker Amplifier Replacement .

### 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 UQ2

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 Radio Rear Speaker Replacement , Radio Front Side Door Lower Speaker Replacement , or Front Upper Speaker Replacement .

#### With RPO U85

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. Gain Control Signal circuit short to ground. Test the Gain Control Signal circuit for a short ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
3. 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.
4. Defective speaker - Replace the appropriate speaker. Refer to Radio Rear Speaker Replacement , Radio Front Side Door Lower Speaker Replacement , or Front Upper Speaker Replacement .