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.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Amplifier B+ | 2 | 2 | -- | --
Antenna Enable Signal | 2 | 2 | -- | --
Amplifier Mute | B1287 02 | 2 | B1287 01 | --
Left Front Speaker Output (+) | B1025 02 | 1 | B1025 01 | --
Left Front Speaker Output (-) | B1025 02 | 1 | B1025 01 | --
Right Front Speaker Output (+) | B1035 02 | 1 | B1035 01 | --
Right Front Speaker Output (-) | B1035 02 | 1 | B1035 01 | --
Left Rear Speaker Output (+) | B1045 02 | 1 | B1045 01 | --
Left Rear Speaker Output (-) | B1045 02 | 1 | B1045 01 | --
Right Rear Speaker Output (+) | B1055 02 | 1 | B1055 01 | --
Right Rear Speaker Output (-) | B1055 02 | 1 | B1055 01 | --
Amplifier Ground | -- | 2 | -- | --
1. No or reduced sound from speaker 2. Amplifier inoperative/no sound from speakers

### 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. 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.

### Diagnostic Aids

• | Improper speaker mounting or loose trim may cause an audible buzz or distortion. Inspect the appropriate speaker and the surrounding interior trim for proper and secure mounting. If the speaker or surrounding interior trim is found to be loose or improperly secured, correctly secure the item.

• | When equipped with an amplifier, it is possible for some individual circuit faults to affect more than one speakers operation. Perform diagnostic tests in the sequence listed to avoid misdiagnosis.

### 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

#### Without Amplifier

Radio ON, verify clear audio is heard from each audio speaker.

⇒ | If audio is inoperative from all speakers, replace the radio.

⇒ | If audio is inoperative from one or more, but not all speakers or the audio emitted from the speakers is not clear, refer to Speaker Circuit Malfunction - without Amplifier.

#### With Amplifier

Radio ON, verify clear audio is heard from each audio speaker.

⇒ | If audio is inoperative from all speakers, refer to Amplifier Circuit Malfunction.

⇒ | If audio is inoperative from one or more, but not all speakers or the audio emitted from the speakers is not clear, refer to Speaker Circuit Malfunction - with Amplifier.

### Circuit/System Testing

#### Speaker Circuit Malfunction - without Amplifier

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 1 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 2 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 appropriate speaker.

#### Amplifier Circuit Malfunction

1. Ignition OFF, disconnect the X1 harness connector at the audio amplifier.
2. Test for less than 10 Ω between the ground circuit terminal 5 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Test for B+ between the battery voltage circuit terminal 8 and ground.

⇒ | If less than the specified value, test the circuit for a short to ground or an open/high resistance.

4. Ignition OFF, disconnect the X3 harness connector at the audio amplifier.
5. Radio ON, test for B+ between the signal circuit terminal 8 and ground.

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

6. Test for 0.6-1.0 V between the amplifier mute circuit terminal 16 and ground.

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

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

#### Speaker Circuit Malfunction - with Amplifier

1. Disconnect the X3 harness connector at the audio amplifier.
2. Radio ON, test for 5.0-7.5 V between the appropriate speaker output circuit terminal listed below and ground.

• | Left front low level audio signal (+) - terminal 12

• | Left front low level audio signal (-) - terminal 10

• | Right front low level audio signal (+) - terminal 9

• | Right front low level audio signal (-) - terminal 11

• | Left rear low level audio signal (+) - terminal 3

• | Left rear low level audio signal (-) - terminal 1

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

• | Right rear low level audio signal (-) - terminal 2

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

3. Ignition OFF, disconnect the X1 and X2 harness connectors at the amplifier.
4. Ignition ON, test for less than 1 V between each of the signal circuit terminals listed below and ground.

• | Left front speaker output (+) - terminal 11 X2

• | Left front speaker output (-) - terminal 12 X2

• | Right front speaker output (+) - terminal 10 X2

• | Right front speaker output (-) - terminal 9 X2

• | Left rear speaker output (+) - terminal 2 X2

• | Left rear speaker output (-) - terminal 1 X2

• | Right rear speaker output (+) - terminal 3 X2

• | Right rear speaker output (-) - terminal 4 X2

• | Subwoofer speaker coil 1 output (+) - terminal 3 X1

• | Subwoofer speaker coil 1 output (-) - terminal 4 X1

• | Subwoofer speaker coil 2 output (+) - terminal 2 X1

• | Subwoofer speaker coil 2 output (-) - terminal 1 X1

⇒ | If greater than the specified range, test both signal circuits of the appropriate speaker for a short to voltage.

5. Ignition OFF, test for infinite resistance between each of the signal circuit terminals listed below and ground.

• | Left front speaker output (+) - terminal 11 X2

• | Left front speaker output (-) - terminal 12 X2

• | Right front speaker output (+) - terminal 10 X2

• | Right front speaker output (-) - terminal 9 X2

• | Left rear speaker output (+) - terminal 2 X2

• | Left rear speaker output (-) - terminal 1 X2

• | Right rear speaker output (+) - terminal 3 X2

• | Right rear speaker output (-) - terminal 4 X2

• | Subwoofer speaker coil 1 output (+) - terminal 3 X1

• | Subwoofer speaker coil 1 output (-) - terminal 4 X1

• | Subwoofer speaker coil 2 output (+) - terminal 2 X1

• | Subwoofer speaker coil 2 output (-) - terminal 1 X1

⇒ | If less than the specified range, test both signal circuits of the appropriate speaker for a short to ground.

6. Ignition OFF, reconnect all harness connectors at the amplifier. Disconnect the harness connector at the appropriate speaker.
7. Radio ON, test for 5.0-7.5 V between the appropriate signal circuit terminals listed below and ground.

• | Front door speakers - terminal 1 and 2

• | Front tweeter speakers - terminal 1 and 2

• | Rear speakers - terminal 1 and 2

• | Subwoofer speaker assembly - terminal A, B, C and D

⇒ | If less than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the amplifier.

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

8. If all circuits test normal, replace the inoperative speaker.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Speaker Replacement Reference

• | Control Module References for Audio Amplifier and Radio replacement, setup, and programming