For 1990-2009 cars

### DTC Descriptors

DTC B1025: LF Audio Output Circuit
DTC B1035: RF Audio Output Circuit
DTC B1045: LR Audio Output Circuit
DTC B1055: RR Audio Output Circuit

### Diagnostic Fault Information

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

### Circuit/System Description

The radio head unit provides four discrete channels to the speakers. Each channel consists of two wires that connect to a speaker. During normal operation, the radio applies approximately 5-6 volts to the plus (+) and minus (-) terminals at the speaker. The terminals attach to the speaker voice coil.

In order for the speaker to produce sound, the amplifier in the radio will raise the voltage on one terminal and lower the voltage on the opposite terminal, then quickly reverse the polarity. The constant switching of the electrical signal causes the voice coil and speaker cone to move rapidly in two directions. The movement of the speaker cone produces sound.

### Conditions for Running the DTC

The following are conditions that must be present in order for the radio to enable the diagnostics.

• | The radio is in the ACCESSORY, RUN, or RAP power mode.

• | The system voltage is at least 9 volts and no more than 16 volts.

### Conditions for Setting the DTC

The following conditions are present for 250 ms or longer.

• | One of the speaker output circuits is shorted to battery.

• | One of the speaker output circuits is shorted to ground.

### Action Taken When the DTC Sets

The radio disables the audio output to the speaker with the current fault, producing no sound from the speaker.

### Conditions for Clearing the DTC

• | The conditions for setting the DTC are no longer present.

• | A history DTC clears after 100 malfunction-free ignition cycles.

• | The radio receives the clear code command from the scan tool.

### Diagnostic Aids

With the use of Co-axial speakers, some sound (Bass or Treble) may be coming from the speakers depending on what circuit has been affected. Adjusting the bass and treble accordingly to identify faulty circuit may help with diagnosis.

### Reference Information

#### Schematic Reference

Radio/Navigation System Schematics

#### Connector End View Reference

Entertainment/Communication Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Scan Tool Data List

#### Special Tools Required

J 39916-A CD and Cassette Diagnostic Audio Kit

### Circuit/System Verification

Verify customer complaint by adjusting speaker outputs through the radio controls, fade and/or balance.

### Circuit/System Testing

1. Test the speaker circuits for an open, short to voltage, or short to ground.

⇒ | Test for 5-6 volt on speaker signal (+) and return (-) circuits during the short condition

2. If the circuit tests normal, test or replace the radio.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Radio Replacement