For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

DTC B1025: Audio Output 1 Left Front Circuit
DTC B1035: Audio Output 2 Right Front Circuit
DTC B1045: Audio Output 3 Left Rear Circuit
DTC B1055: Audio Output 4 Right Rear Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Left Front Speaker Output (+) | B1025* | 1 | B1025* | --
Left Front Speaker Output (-) | B1025* | 1 | B1025* | --
Right Front Speaker Output (+) | B1035* | 1 | B1035* | --
Right Front Speaker Output (-) | B1035* | 1 | B1035* | --
Left Rear Speaker Output (+) | B1045* | 1 | B1045* | --
Left Rear Speaker Output (-) | B1045* | 1 | B1045* | --
Right Rear Speaker Output (+) | B1055* | 1 | B1055* | --
Right Rear Speaker Output (-) | B1055* | 1 | B1055* | --
1. No or reduced sound from speaker * Noticeable audio distortion possible

### Circuit/System Description

Each of the audio output channel circuits (+) and (-), at the radio and at the amplifier (if equipped) have a DC bias voltage that is one half of the battery voltage. When using a DMM, each of the audio output channel circuits will measure approximately 6.5V DC. The audio being played on the system is produced by a varying AC voltage that is centered around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker cone to move and produce sound. This voltage will vary depending on what type of audio is being listened to, talk or music, and type of music, as well as the volume setting of the system. Low volume and talk settings will measure around 1V AC and less, where constant music may measure 3V AC and slightly higher.

### Conditions for Running the DTC

The radio is ON.

### Conditions for Setting the DTC

A short to voltage or short to ground is detected on the specified (+) or (-) signal circuit.

### Action Taken When the DTC Sets

The radio disables audio output on the appropriate channel

### Conditions for Clearing the DTC

• | A current DTC will clear when the conditions for setting the DTC are no longer present.

• | A history DTC will clear after 100 malfunction free ignition cycles.

### Reference Information

#### Schematic Reference

Radio/Navigation System Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Radio/Audio System Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Radio ON, adjust the fade and balance controls on the radio to test all four channels individually. Each of the four channels should produce clear and even sound.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate speaker.
2. Radio ON, test for 5.0-7.5 volts between the signal circuit terminals listed below and ground.

• | Speaker terminal A

• | Speaker terminal B

• | Tweeter terminal 1

• | Tweeter terminal 2

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.

3. If all circuits test normal, replace the speaker.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Speaker Replacement Reference

• | Control Module References for radio replacement, setup, and programming