GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Caprice WM 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC B1025, B1035, B1045, or B1055

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 B1025 04: Audio Output 1 Left Front Circuit Open

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 B1035 04: Audio Output 2 Left Front Circuit Open

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 B1045 04: Audio Output 3 Left Front Circuit Open

DTC B1055 01:  Audio Output 4 Right Rear Circuit Short to Battery

DTC B1055 02:  Audio Output 4 Right Rear Circuit Short to Ground

DTC B1055 04: Audio Output 4 Left Front Circuit Open

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Amplifier B+

--

1

--

--

Left Front Speaker Output (+) Signal

B1025 02, *

B1025 04, *

B1025 01, *

--

Left Front Speaker Output (-) Signal

B1025 02, *

B1025 04, *

B1025 01, *

--

Right Front Speaker Output (+) Signal

B1035 02, *

B1035 04, *

B1035 01, *

--

Right Front Speaker Output (-) Signal

B1035 02, *

B1035 04, *

B1035 01, *

--

Left Rear Speaker Output (+) Signal

B1045 02, *

B1045 04, *

B1045 01, *

--

Left Rear Speaker Output (-) Signal

B1045 02, *

B1045 04, *

B1045 01, *

--

Right Rear Speaker Output (+) Signal

B1055 02*

B1055 04*

B1055 01, *

--

Right Rear Speaker Output (-) Signal

B1055 02*

B1055 04*

B1055 01, *

--

Rear Subwoofer Speaker Outputs (+) Signal

2

2

2

--

Rear Subwoofer Speaker Outputs (-) Signal

2

2

2

--

Center Speaker Output Signal (+)

3

3

3

--

Center Speaker Output Signal (-)

3

3

3

--

Amplifier Ground

--

1

--

--

1. Amplifier inoperative/no sound from speakers.

2. No or reduced sound from subwoofer.

3. No sound from center speaker.

* Noticeable audio distortion possible.

Circuit/System Description

Each of the audio output channel circuits (+) and (-), at the radio and audio amplifier 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. The amplifier may only supplied an amplified signal to the subwoofers, or on the premium audio systems, the amplifier will amplify all of the audio signals. The amplifier can not set DTCs.

Conditions for Running the DTC
    • The radio is ON.
    • Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

B1025 01, B1035 01, B1045 01, B1055 01

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

B1025 02, B1035 02, B1045 02, B1055 02

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

B1025 04, B1035 04, B1045 04, B1055 04

An open/high resistance is detected on the specified (+) or (-) signal circuit.

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

  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 terminal A and ground.
    3. ⇒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 volts between the signal circuit terminal B and ground.
    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.
  4. If all circuits test normal, replace the speaker.

With Amplifier -- Front Speaker Testing UQG

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

With Amplifier -- Rear Speaker Testing UQG

  1. Ignition OFF, disconnect the amplifier and the appropriate speaker harness connectors.
  2. Radio ON, test for 5.0-7.5 V between the signal circuit terminal A and ground.
    3. ⇒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.
    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.
  4. Ignition OFF, reconnect the harness connector at the audio amplifier.
  5. Radio ON, test for 5.0-7.5 V between the signal circuit terminal A and ground at the appropriate speaker.
    6. ⇒If not within the specified range, replace the amplifier.
  6. Radio ON, test for 5.0-7.5 V between the signal circuit terminal B and ground at the appropriate speaker.
    7. ⇒If not within the specified range, replace the amplifier.
  7. If all circuits test normal, replace the speaker.

With Amplifier -- Speaker Testing RHD -- UQA

  1. Ignition OFF, disconnect the X1 harness connector at the amplifier.
  2. Radio ON, test for 5.0-7.5 V between the terminals listed below and ground.
    3. • 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 amplifier.

With Amplifier -- Speaker Testing LHD -- UQA

  1. Ignition OFF, disconnect the X1 harness connector at the amplifier.
  2. Radio ON, test for 5.0-7.5 V between the terminals listed below and ground.
    3. • Left front low level audio signal (+) - terminal 14
    • Left front low level audio signal (-) - terminal 6
    • Right front low level audio signal (+) - terminal 15
    • Right front low level audio signal (-) - terminal 7
    • Left rear low level audio signal (+) - terminal 12
    • Left rear low level audio signal (-) - terminal 4
    • Right rear low level audio signal (+) - terminal 13
    • Right rear low level audio signal (-) - terminal 5
    ⇒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 amplifier.

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