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 Descriptors

DTC B1025 01: Audio Output 1 Left Front Circuit Short to Battery
DTC B1025 02: Audio Output 1 Left Front Circuit Short to Ground
DTC B1035 01: Audio Output 2 Right Front Circuit Short to Battery
DTC B1035 02: Audio Output 2 Right Front Circuit Short to Ground
DTC B1045 01: Audio Output 3 Left Rear Circuit Short to Battery
DTC B1045 02: Audio Output 3 Left Rear Circuit Short to Ground
DTC B1055 01: Audio Output 4 Right Rear Circuit Short to Battery
DTC B1055 02: Audio Output 4 Right Rear Circuit Short to Ground

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Amplifier B+ | 2 | 2 | -- | --
Entertainment Remote Enable Signal | 2 | 2 | -- | --
Audio Signal Circuit (+)/ Low Level Audio Signal Circuit (+) | B10XX 02*,** | 1 | B10XX 01*,** | --
Audio Signal Circuit (-)/ Low Level Audio Signal Circuit (-) | B10XX 02*,** | 1 | B10XX 01*,** | --
Radio Audio Mute Signal | B1287 02 | B1287 04 | B1287 01 | --
Amplifier Ground | -- | 2 | -- | --
1. No or reduced sound from speaker 2. Amplifier inoperative/no sound from speakers * Sets associated speaker DTC with appropriate symptom type ** Noticeable audio distortion possible

### Circuit/System Description

Each of the audio output channel circuits (+) and (-), at the radio and audio 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 6.5 V 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 3 V AC and slightly higher. In an amplified audio system, these similar AC voltage measurements may be slightly higher on the output of the amplifier, and the typical AC voltage readings at the output of the radio are less than 1V AC.

### Conditions for Running the DTC

• | Radio ON.

• | Battery voltage must be between 9-16 V.

### Conditions for Setting the DTC

The radio detects a short to voltage or short to ground in any of the low level audio signal circuits (+) and (-).

### Action Taken When the DTC Sets

No sound is present from one or more of the speakers.

### Conditions for Clearing the DTC

• | The condition responsible for setting the DTC no longer exists.

• | A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

### 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 Testing

#### Without Amplifier without UK6

1. Ignition OFF, disconnect the harness connector at the appropriate speaker.
2. Radio ON, test for 5.0-7.5 V between the signal circuit terminal A and ground.

⇒ | 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. Test for 5.0-7.5 V between the signal circuit terminal B and ground.

⇒ | 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.

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

#### Without Amplifier with UK6

1. Ignition OFF, disconnect the X2 harness connector at the Auxiliary Radio/HVAC Control.
2. Radio ON, test for 5.0-7.5 V between the appropriate signal circuit terminal listed below and ground.

• | Left Rear Low Level Audio Signal (+) - terminal 1

• | Left Rear Low Level Audio Signal (-) - terminal 2

• | Right Rear Low Level Audio Signal (+) - terminal 3

• | Right Rear Low Level Audio Signal (-) - terminal 4

⇒ | 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. Ignition OFF, reconnect the X2 harness connector at the Auxiliary Radio/HVAC Control. Disconnect the harness connector at the appropriate speaker.
4. Radio ON, test for 5.0-7.5 V between the signal circuit terminal A and ground.

⇒ | 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 for front speaker circuits, replace the radio; for rear speaker circuits, replace the auxiliary radio/HVAC control.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal for front speaker circuits, replace the radio; for rear speaker circuits, replace the auxiliary radio/HVAC control.

5. Test for 5.0-7.5 V between the signal circuit terminal B and ground.

⇒ | 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 for front speaker circuits, replace the radio; for rear speaker circuits, replace the auxiliary radio/HVAC control.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal for front speaker circuits, replace the radio; for rear speaker circuits, replace the auxiliary radio/HVAC control.

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

#### With Amplifier UQG without UK6

1. Ignition OFF, disconnect the X3 harness connector at the audio amplifier.
2. Radio ON, test for 5.0-7.5 V between the appropriate signal circuit terminal listed below and ground.

• | Left front low level audio signal (+) - terminal 5

• | Left front low level audio signal (-) - terminal 13

• | Right front low level audio signal (+) - terminal 6

• | Right front low level audio signal (-) - terminal 14

• | Left rear low level audio signal (+) - terminal 7

• | Left rear low level audio signal (-) - terminal 15

• | Right rear low level audio signal (+) - terminal 8

• | Right rear low level audio signal (-) - terminal 16

⇒ | 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 audio amplifier.

#### With Amplifier UQA/UQS without UK6

1. Ignition OFF, disconnect the X3 harness connector at the audio amplifier.
2. Radio ON, test for 5.0-7.5 V between the appropriate signal circuit terminal listed below and ground.

• | Left front low level audio signal (+) - terminal 15

• | Left front low level audio signal (-) - terminal 7

• | Right front low level audio signal (+) - terminal 14

• | Right front low level audio signal (-) - terminal 6

• | Left rear low level audio signal (+) - terminal 13

• | Left rear low level audio signal (-) - terminal 5

• | Right rear low level audio signal (+) - terminal 12

• | Right rear low level audio signal (-) - terminal 4

⇒ | 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 audio amplifier.

#### With Amplifier UQG with UK6

1. Ignition OFF, disconnect the X2 harness connector at the Auxiliary Radio/HVAC Control.
2. Radio ON, test for 5.0-7.5 V between the appropriate signal circuit terminal listed below and ground.

• | Left Rear Low Level Audio Signal (+) - terminal 1

• | Left Rear Low Level Audio Signal (-) - terminal 2

• | Right Rear Low Level Audio Signal (+) - terminal 3

• | Right Rear Low Level Audio Signal (-) - terminal 4

⇒ | 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. Ignition OFF, reconnect the X2 harness connector at the Auxiliary Radio/HVAC Control. Disconnect the X3 harness connector at the audio amplifier.
4. Radio ON, test for 5.0-7.5 V between the appropriate signal circuit terminal listed below and ground.

• | Left rear low level audio signal (+) - terminal 7

• | Left rear low level audio signal (-) - terminal 15

• | Right rear low level audio signal (+) - terminal 8

• | Right rear low level audio signal (-) - terminal 16

⇒ | 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 auxiliary radio/HVAC control.

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

5. Test for 5.0-7.5 V between the appropriate signal circuit terminal listed below and ground.

• | Left front low level audio signal (+) - terminal 5

• | Left front low level audio signal (-) - terminal 13

• | Right front low level audio signal (+) - terminal 6

• | Right front low level audio signal (-) - terminal 14

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

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

6. If all circuits test normal, replace the audio amplifier.

#### With Amplifier UQA/UQS with UK6

1. Ignition OFF, disconnect the X2 harness connector at the Auxiliary Radio/HVAC Control.
2. Radio ON, test for 5.0-7.5 V between the appropriate signal circuit terminal listed below and ground.

• | Left Rear Low Level Audio Signal (+) - terminal 1

• | Left Rear Low Level Audio Signal (-) - terminal 2

• | Right Rear Low Level Audio Signal (+) - terminal 3

• | Right Rear Low Level Audio Signal (-) - terminal 4

⇒ | 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. Ignition OFF, reconnect the X2 harness connector at the Auxiliary Radio/HVAC Control. Disconnect the X3 harness connector at the audio amplifier.
4. Radio ON, test for 5.0-7.5 V between the appropriate signal circuit terminal listed below and ground.

• | Left rear low level audio signal (+) - terminal 13

• | Left rear low level audio signal (-) - terminal 5

• | Right rear low level audio signal (+) - terminal 12

• | Right rear low level audio signal (-) - terminal 4

⇒ | 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 auxiliary radio/HVAC control.

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

5. Test for 5.0-7.5 V between the appropriate signal circuit terminal listed below and ground.

• | Left front low level audio signal (+) - terminal 15

• | Left front low level audio signal (-) - terminal 7

• | Right front low level audio signal (+) - terminal 14

• | Right front low level audio signal (-) - terminal 6

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

6. If all circuits test normal, replace the audio amplifier.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Speaker Replacement Reference

• | Control Module References for audio amplifier, radio or auxiliary radio/HVAC control replacement, setup, and programming.